Tumbleweed overheats in KDE but not in XFCE

since a few months I encounter the following:
After starting up my desktop with Tumbleweed-KDE I use it on and off during the day. After about 6 hours, suddenly the temperature of the PCI adapter rises and the system is almost unresponsive. (almost: about once every 3 minutes a new value becomes visible in sensors, all the time well above acceptable values)
The command in the console “watch sensors” then shows a temperature of:
composite: 72 C
Sensor 1: 60 C
Sensor 2: 90 C.
Testing promptly after startup with 10 x writing and deleting a video (4 GB) raises the temperature to about 85 C, the system will not hang.

Since looking through Internet I found that KDE is resource-heavy, so I tried a lighter GUI: XFCE.
The test with 10 x writing and deleting gave the same temperature effect.
But even while using the computer on-and-off during 24 hours, no hang occurred.

I would really like to know what happens in KDE that does not happen in XFCE, if only a pointer to a package that causes sudden overheating after about 6 hours.

Daniel

Run top or system monitor to see what process is hogging the CPU

How clean is the inside of your system? Are the fans and heatsinks, including those inside the PSU, overdue for cleaning? Is there an input air filter that’s never been cleaned? What are the PC specs (inxi -Fz)?

Asking why your system overheats and telling only it’s a “desktop with Tumbleweed-KDE” is insane, in my opinion of course.

Which temperature are talking about? Make sure you configured sensors and show complete output:

erlangen:~ # sensors 
k10temp-pci-00c3 
Adapter: PCI adapter 
Tctl:         +31.8°C   
Tccd1:        +31.8°C   

nvme-pci-0100 
Adapter: PCI adapter 
Composite:    +41.9°C  (low  = -273.1°C, high = +84.8°C) 
                       (crit = +84.8°C) 
Sensor 1:     +41.9°C  (low  = -273.1°C, high = +65261.8°C) 
Sensor 2:     +40.9°C  (low  = -273.1°C, high = +65261.8°C) 

nct6687-isa-0a20 
Adapter: ISA adapter 
VIN0:               1.01 V  (min =  +0.00 V, max =  +0.00 V) 
VIN1:             992.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN2:             992.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN3:             672.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN4:             256.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN5:             848.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN6:             752.00 mV (min =  +0.00 V, max =  +0.00 V) 
VIN7:               1.54 V  (min =  +0.00 V, max =  +0.00 V) 
VCC:                3.34 V  (min =  +0.00 V, max =  +0.00 V) 
VTT:                1.82 V  (min =  +0.00 V, max =  +0.00 V) 
fan1:              511 RPM  (min =    0 RPM) 
fan2:                0 RPM  (min =    0 RPM) 
fan3:                0 RPM  (min =    0 RPM) 
fan4:                0 RPM  (min =    0 RPM) 
fan5:                0 RPM  (min =    0 RPM) 
fan6:                0 RPM  (min =    0 RPM) 
fan7:                0 RPM  (min =    0 RPM) 
fan8:                0 RPM  (min =    0 RPM) 
fan9:                0 RPM  (min =    0 RPM) 
fan10:               0 RPM  (min =    0 RPM) 
AMD TSI Addr 98h:  +31.0°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = AMD AMDSI 
Diode 0 (curr):    +37.5°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = thermal diode 
Thermistor 15:     +35.0°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = thermistor 
Thermistor 1:      +39.5°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = thermistor 
Thermistor 16:     +33.0°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = thermistor 
Thermistor 0:      +34.0°C  (low  =  +0.0°C) 
                            (high =  +0.0°C, hyst =  +0.0°C) 
                            (crit =  +0.0°C)  sensor = thermistor 
Thermistor 15:     +35.5°C  (low  =  +0.0°C) 
                            (high = +126.0°C, hyst = +30.0°C) 
                            (crit =  +0.0°C)  sensor = thermistor 
intrusion0:       ALARM 
beep_enable:      disabled 

amdgpu-pci-2b00 
Adapter: PCI adapter 
vddgfx:      787.00 mV  
fan1:         974 RPM  (min =    0 RPM, max = 3500 RPM) 
edge:         +51.0°C  (crit = +97.0°C, hyst = -273.1°C) 
PPT:           3.17 W  (cap =  36.00 W) 

erlangen:~ #

KDE isn’t resource heavy This is a widespread misconception which is is readily demonstrated for my desktop by running “systemd-cgtop -1 --cpu=time user.slice/user-1000.slice/user@1000.service”:

Control Group                                                                                      Tasks         CPU Time   Memory  Input/s Output/s
user.slice/user-1000.slice/user@1000.service                                                         802  17min 3.983819s     5.8G        -        - 
**user.slice/user-1000.slice/user@1000.service/app.slice                                               663  15min 8.685894s     3.9G        -        - **
user.slice/user-1000.slice/user…ice/app.slice/app-firefox-c800f56dd67f47318d752df8505afd78.scope     401 14min 34.305594s     2.2G        -        - 
**user.slice/user-1000.slice/user@1000.service/session.slice                                           101  1min 48.835494s   670.3M        -        - **
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kwin_x11.service                    16       39.984061s    84.0M        -        - 
user.slice/user-1000.slice/user@1000.service/session.slice/pipewire-pulse.service                      2       26.594446s    58.5M        -        - 
user.slice/user-1000.slice/user…fusr\x2fbin\x2fkalendarac-4a7fd157b5784669971b74023a4263a7.scope     172       24.283687s   731.0M        -        - 
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service                 24       22.540458s   376.1M        -        - 
user.slice/user-1000.slice/user@1000.service/session.slice/pipewire.service                            2       16.089782s    11.3M        -        - 
user.slice/user-1000.slice/user@1000.service/background.slice                                         36        6.190851s     1.2G        -        - 
user.slice/user-1000.slice/user….slice/app-org.kde.kmail2-8403c2952f0f4e9895352386507e876d.scope      52        4.859673s   421.8M        -        - 
user.slice/user-1000.slice/user…slice/app-org.kde.konsole-3313b5bd4a7f4650b32a2b0aad5f6a1b.scope      12        4.084765s   520.7M        -        - 
user.slice/user-1000.slice/user@1000.service/background.slice/kde-baloo.service                        3        3.832130s     1.1G        -        - 
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kded.service                        15        1.338416s    50.4M        -        - 
user.slice/user-1000.slice/user@1000.service/session.slice/dbus.service                                1        1.192530s     2.3M        -        - 
...
karl@erlangen:~> 

App slice is 15min 8sec vs. session slice 1min 48 sec.

High temperatures may be caused by a hardware failure, bad design decisions or some software with rogue behaviour.

erlangen:~ # inxi -zaFmy132 
System:    Kernel: 5.18.11-1-default arch: x86_64 bits: 64 compiler: gcc v: 12.1.1 
             parameters: BOOT_IMAGE=/boot/vmlinuz-5.18.11-1-default root=UUID=0e58bbe5-eff7-4884-bb5d-a0aac3d8a344 quiet loglevel=2 
             plymouth.enable=0 mitigations=auto 
           Console: pty pts/1 wm: kwin_x11 DM: SDDM Distro: openSUSE Tumbleweed 20221119 
Machine:   Type: Desktop System: Micro-Star product: MS-7C56 v: 2.0 serial: N/A 
           Mobo: Micro-Star model: B550-A PRO (MS-7C56) v: 2.0 serial: <filter> UEFI: American Megatrends LLC. v: A.90 
             date: 03/17/2022 
Battery:   Device-1: hidpp_battery_0 model: Logitech Wireless Mouse M510 serial: <filter> charge: 55% (should be ignored) 
             rechargeable: yes status: discharging 
           Device-2: hidpp_battery_1 model: Logitech Wireless Keyboard K540/K545 serial: <filter> charge: 100% (should be 
             ignored) rechargeable: yes status: discharging 
Memory:    RAM:total: 31.26 GiB used: 4.27 GiB (13.7%) 
           Array-1:capacity: 128 GiB slots: 4 EC: None max-module-size: 32 GiB note: est. 
           Device-1: DIMM 0 type: no module installed 
           Device-2: DIMM 1 type: DDR4 detail: synchronous unbuffered (unregistered) size: 16 GiB speed: 3200 MT/s volts:
             curr: 1.2 min: 1.2 max: 1.2 width (bits):data: 64 total: 64 manufacturer: Corsair part-no: CMK32GX4M2E3200C16 
             serial: N/A 
           Device-3: DIMM 0 type: no module installed 
           Device-4: DIMM 1 type: DDR4 detail: synchronous unbuffered (unregistered) size: 16 GiB speed: 3200 MT/s volts:
             curr: 1.2 min: 1.2 max: 1.2 width (bits):data: 64 total: 64 manufacturer: Corsair part-no: CMK32GX4M2E3200C16 
             serial: N/A 
CPU:       Info:model: AMD Ryzen 5 5600X socket: AM4 bits: 64 type: MT MCP arch: Zen 3 gen: 4 level: v3 note: check built: 2021-22 
             process: TSMC n7 (7nm) family: 0x19 (25) model-id: 0x21 (33) stepping: 2 microcode: 0xA201205 
           Topology:cpus: 1x cores: 6 tpc: 2 threads: 12 smt: enabled cache:L1: 384 KiB desc: d-6x32 KiB; i-6x32 KiB L2: 3 MiB 
             desc: 6x512 KiB L3: 32 MiB desc: 1x32 MiB 
           Speed (MHz):avg: 2200 min/max: 2200/3700 boost: enabled base/boost: 3700/4650 scaling:driver: acpi-cpufreq 
             governor: schedutil volts: 1.1 V ext-clock: 100 MHz cores:1: 2200 2: 2200 3: 2200 4: 2200 5: 2200 6: 2200 7: 2200 
             8: 2200 9: 2200 10: 2200 11: 2200 12: 2200 bogomips: 88804 
           Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm 
           Vulnerabilities: ...
Graphics:  Device-1: AMD Lexa PRO [Radeon 540/540X/550/550X / RX 540X/550/550X] vendor: Sapphire driver: amdgpu v: kernel 
             arch: GCN-4 code: Arctic Islands process: GF 14nm built: 2016-20 pcie:gen: 3 speed: 8 GT/s lanes: 8 ports:
             active: HDMI-A-1 empty: DP-1,DVI-D-1 bus-ID: 2b:00.0 chip-ID: 1002:699f class-ID: 0300 temp: 49.0 C 
           Display: x11 server: X.Org v: 21.1.4 with: Xwayland v: 22.1.5 compositor: kwin_x11 driver:X:loaded: amdgpu 
             unloaded: fbdev,modesetting,vesa dri: radeonsi gpu: amdgpu display-ID: :0 screens: 1 
           Screen-1: 0 s-res: 3840x2160 s-dpi: 192 s-size: 508x285mm (20.00x11.22") s-diag: 582mm (22.93") 
           Monitor-1: HDMI-A-1 mapped: HDMI-A-0 model: Samsung LU28R55 serial: <filter> built: 2038 res: 3840x2160 hz: 60 
             dpi: 154 gamma: 1.2 size: 632x360mm (24.88x14.17") diag: 727mm (28.6") ratio: 16:9 modes:max: 3840x2160 min: 720x400 
           API: OpenGL v: 4.6 Mesa 22.2.3 renderer: AMD Radeon RX 550 / 550 Series (polaris12 LLVM 15.0.5 DRM 3.46 
             5.18.11-1-default) direct render: Yes 
Audio:     Device-1: AMD Baffin HDMI/DP Audio [Radeon RX 550 640SP / 560/560X] vendor: Sapphire driver: snd_hda_intel v: kernel 
             pcie:gen: 3 speed: 8 GT/s lanes: 8 bus-ID: 2b:00.1 chip-ID: 1002:aae0 class-ID: 0403 
           Device-2: Advanced Micro Devices [AMD] Starship/Matisse HD Audio vendor: Micro-Star MSI driver: snd_hda_intel 
             v: kernel pcie:gen: 4 speed: 16 GT/s lanes: 16 bus-ID: 2d:00.4 chip-ID: 1022:1487 class-ID: 0403 
           Sound API: ALSA v: k5.18.11-1-default running: yes 
           Sound Server-1: PulseAudio v: 16.1 running: no 
           Sound Server-2: PipeWire v: 0.3.60 running: yes 
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Micro-Star MSI driver: r8169 v: kernel pcie:
             gen: 1 speed: 2.5 GT/s lanes: 1 port: e000 bus-ID: 2a:00.0 chip-ID: 10ec:8168 class-ID: 0200 
           IF: enp42s0 state: up speed: 1000 Mbps duplex: full mac: <filter> 
Drives:    Local Storage:total: 3.64 TiB used: 1.54 TiB (42.2%) 
           ID-1: /dev/nvme0n1 maj-min: 259:0 vendor: Samsung model: SSD 970 EVO Plus 2TB size: 1.82 TiB block-size:
             physical: 512 B logical: 512 B speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter> rev: 2B2QEXM7 temp: 41.9 C 
             scheme: GPT 
           SMART: yes health: PASSED on: 26d 4h cycles: 883 read-units: 28,007,523 [14.3 TB] written-units: 24,414,094 [12.5 TB] 
           ID-2: /dev/sda maj-min: 8:0 vendor: Crucial model: CT2000BX500SSD1 family: Micron Client SSDs size: 1.82 TiB 
             block-size:physical: 512 B logical: 512 B sata: 3.3 speed: 6.0 Gb/s type: SSD serial: <filter> rev: 030 temp: 32 C 
             scheme: GPT 
           SMART: yes state: enabled health: PASSED on: 1y 13d 10h cycles: 1957 written: 3.25 TiB 
Partition: ID-1: / raw-size: 1.77 TiB size: 1.77 TiB (100.00%) used: 467.77 GiB (25.8%) fs: btrfs block-size: 4096 B 
...
Sensors:   System Temperatures:cpu: 35.4 C mobo: N/A gpu: amdgpu temp: 51.0 C 
           Fan Speeds (RPM):fan-1: 498 fan-2: 0 fan-3: 0 fan-4: 0 fan-5: 0 fan-6: 0 fan-7: 0 fan-8: 0 fan-9: 0 fan-10: 0 
             gpu: amdgpu fan: 971 
Info:      Processes: 347 Uptime: 2h 10m wakeups: 18 Init: systemd v: 252 default: graphical tool: systemctl Compilers:gcc: 12.2.1 
           alt: 12 Packages:pm: dpkg pkgs: 0 tools: apt,apt-get,aptitude pm: rpm pkgs: N/A note: see --rpm tools: yast,zypper 
           pm: flatpak pkgs: 0 Shell: Bash (su) v: 5.2.9 running-in: konsole inxi: 3.3.23 
erlangen:~ #

I’ll have the system running overnight whilst at the same time running Psensor in order to see a.o. CPU activity and report back

The system housing was opened, vacuumed and run without replacing the cover. This was no improvement at all.
Since the problem only occurs whils running KDE and not when running XFCE, dust does not seem a factor.
Specs:
Lenovo-daan:~ # inxi -Fz
System:
Kernel: 6.0.8-1-default arch: x86_64 bits: 64 Desktop: Xfce v: 4.16.1
Distro: openSUSE Tumbleweed 20221118
Machine:
Type: Desktop System: LENOVO product: 90H0004EMH v: ideacentre 720-18IKL
serial: <filter>
Mobo: LENOVO model: 36C5 v: SDK0J40709 WIN 3259623979395 serial: N/A
UEFI-[Legacy]: LENOVO v: O2TKT42A date: 11/09/2017
CPU:
Info: quad core model: Intel Core i5-7600K bits: 64 type: MCP cache:
L2: 1024 KiB
Speed (MHz): avg: 3800 min/max: 800/4200 cores: 1: 3800 2: 3800 3: 3800
4: 3800
Graphics:
Device-1: Intel HD Graphics 630 driver: i915 v: kernel
Display: x11 server: X.Org v: 21.1.4 with: Xwayland v: 22.1.5 driver: X:
loaded: modesetting unloaded: fbdev,vesa gpu: i915 resolution:
1: 1920x1080~60Hz 2: 1920x1200~60Hz
OpenGL: renderer: Mesa Intel HD Graphics 630 (KBL GT2) v: 4.6 Mesa 22.2.3
Audio:
Device-1: Intel 200 Series PCH HD Audio driver: snd_hda_intel
Sound Server-1: ALSA v: k6.0.8-1-default running: yes
Sound Server-2: PulseAudio v: 16.1 running: yes
Sound Server-3: PipeWire v: 0.3.60 running: yes
Network:
Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
driver: r8169
IF: enp3s0 state: up speed: 1000 Mbps duplex: full mac: <filter>
Device-2: Intel Dual Band Wireless-AC 3165 Plus Bluetooth driver: iwlwifi
IF: wlp4s0 state: down mac: <filter>
Bluetooth:
Device-1: Intel Bluetooth wireless interface type: USB driver: btusb
Report: rfkill ID: hci0 rfk-id: 0 state: down bt-service: enabled,running
rfk-block: hardware: no software: yes address: see --recommends
Drives:
Local Storage: total: 11.03 TiB used: 6.1 TiB (55.3%)
ID-1: /dev/nvme0n1 vendor: Samsung model: MZVLW128HEGR-000L1
size: 119.24 GiB
ID-2: /dev/sda vendor: Western Digital model: WD4000FYYZ-01UL1B2
size: 3.64 TiB
ID-3: /dev/sdb type: USB model: 1Intenso External USB size: 3.64 TiB
ID-4: /dev/sdc type: USB vendor: Western Digital model: WD20SMZW-11JW8S0
size: 1.82 TiB
ID-5: /dev/sdd type: USB vendor: Toshiba model: External USB 3.0
size: 1.82 TiB
Partition:
ID-1: / size: 44.36 GiB used: 28 GiB (63.1%) fs: btrfs dev: /dev/nvme0n1p5
ID-2: /home size: 58.72 GiB used: 53.95 GiB (91.9%) fs: btrfs
dev: /dev/nvme0n1p6
ID-3: /opt size: 44.36 GiB used: 28 GiB (63.1%) fs: btrfs
dev: /dev/nvme0n1p5
ID-4: /tmp size: 44.36 GiB used: 28 GiB (63.1%) fs: btrfs
dev: /dev/nvme0n1p5
ID-5: /var size: 44.36 GiB used: 28 GiB (63.1%) fs: btrfs
dev: /dev/nvme0n1p5
Swap:
ID-1: swap-1 type: partition size: 15.54 GiB used: 32 MiB (0.2%)
dev: /dev/nvme0n1p7
Sensors:
System Temperatures: cpu: 33.0 C mobo: N/A
Fan Speeds (RPM): N/A
Info:
Processes: 390 Uptime: 4h 53m Memory: 15.53 GiB used: 5.06 GiB (32.6%)
Shell: Bash inxi: 3.3.21

Firstly: Danke für dein Vertrauen in meinem Geisteszustand!

Secondly:
Lenovo-daan:~ # sensors
acpitz-acpi-0
Adapter: ACPI interface
temp1: +27.8°C (crit = +119.0°C)
temp2: +29.8°C (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Package id 0: +33.0°C (high = +80.0°C, crit = +100.0°C)
Core 0: +33.0°C (high = +80.0°C, crit = +100.0°C)
Core 1: +30.0°C (high = +80.0°C, crit = +100.0°C)
Core 2: +31.0°C (high = +80.0°C, crit = +100.0°C)
Core 3: +30.0°C (high = +80.0°C, crit = +100.0°C)

iwlwifi_1-virtual-0
Adapter: Virtual device
temp1: N/A

nvme-pci-0200
Adapter: PCI adapter
Composite: +29.9°C (low = -273.1°C, high = +68.8°C)
(crit = +71.8°C)
Sensor 1: +29.9°C (low = -273.1°C, high = +65261.8°C)
Sensor 2: +36.9°C (low = -273.1°C, high = +65261.8°C)

Of course, this when running XFCE
In my earlier reply I put the output of inxi -Fz. I don’t know the correct way: should I just repeat it here or is referral sufficient?

There is no need to repeat info, but a good idea to enclose commands and output within [noparse]

...

[/noparse] tags. Refer to the’#’ button in the forum editor (or type them manually).

inxi output is comprehensive and adequate. My 6700K has somewhat lower temperatures when running KDE/Tumbleweed:

**6700K:~ #** sensors 
nct6791-isa-0290 
Adapter: ISA adapter 
Vcore:                 368.00 mV (min =  +0.00 V, max =  +1.74 V) 
in1:                     1.68 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
AVCC:                    3.38 V  (min =  +2.98 V, max =  +3.63 V) 
+3.3V:                   3.38 V  (min =  +2.98 V, max =  +3.63 V) 
in4:                     1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
in5:                     1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
in6:                     1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
3VSB:                    3.30 V  (min =  +2.98 V, max =  +3.63 V) 
Vbat:                    3.12 V  (min =  +2.70 V, max =  +3.63 V) 
in9:                     1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
in10:                    0.00 V  (min =  +0.00 V, max =  +0.00 V) 
in11:                  960.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM 
in12:                    1.21 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
in13:                    1.27 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
in14:                    1.07 V  (min =  +0.00 V, max =  +0.00 V)  ALARM 
fan1:                     0 RPM  (min =    0 RPM) 
fan2:                   488 RPM  (min =    0 RPM) 
fan3:                     0 RPM  (min =    0 RPM) 
fan4:                     0 RPM  (min =    0 RPM) 
fan5:                     0 RPM  (min =    0 RPM) 
fan6:                     0 RPM  (min =    0 RPM) 
SYSTIN:                 +26.0°C  (high =  +0.0°C, hyst =  +0.0°C)  ALARM  sensor = thermistor 
CPUTIN:                 +28.0°C  (high = +80.0°C, hyst = +75.0°C)  sensor = thermistor 
AUXTIN0:                +25.5°C    sensor = thermistor 
AUXTIN1:               -128.0°C    sensor = thermistor 
AUXTIN2:                +28.0°C    sensor = thermistor 
AUXTIN3:                +22.0°C    sensor = thermistor 
PECI Agent 0:           +25.0°C  (high = +80.0°C, hyst = +75.0°C) 
                                 (crit = +100.0°C) 
PCH_CHIP_CPU_MAX_TEMP:   +0.0°C   
PCH_CHIP_TEMP:           +0.0°C   
PCH_CPU_TEMP:            +0.0°C   
intrusion0:            ALARM 
intrusion1:            ALARM 
beep_enable:           disabled 

pch_skylake-virtual-0 
Adapter: Virtual device 
temp1:        +37.0°C   

coretemp-isa-0000 
Adapter: ISA adapter 
Package id 0:  +29.0°C  (high = +80.0°C, crit = +100.0°C) 
Core 0:        +23.0°C  (high = +80.0°C, crit = +100.0°C) 
Core 1:        +29.0°C  (high = +80.0°C, crit = +100.0°C) 
Core 2:        +23.0°C  (high = +80.0°C, crit = +100.0°C) 
Core 3:        +22.0°C  (high = +80.0°C, crit = +100.0°C) 

**6700K:~ #**

A single fan operates at 488 RPM. Power uptake is 21 Watts when idle. Temperatures stay low when running a youtube video. Provide the output of “systemd-cgtop --cpu=time …” as shown above.

I am unsure whether I need to add: The output of the command is only useful when big temperature spikes have occurred since booting.

As when going to the dentist, pain stops on entering the premises! This is what I found:
After a full night running the system with KDE and using it the next day again on-and-off no overheating occurred. Psensors showed a temparature never over 85 C.
I’ll keep using the system as usual and if normal operation continues will not come back to this thread - at this moment it is too early to consider it solved…

OUCH! after restart this morning, I used the system normally (for me normal = with frequent interruptions) for about 5 hours. Then suddenly, for no visible reasons, the temperature very quickly rose to unacceptable levels resulting in a hang - high temperature visible on Sensor 2 and Composite. I was using Kpat when that happened.
Every few minutes there was a bit of action in the graph of Psensor, whilst the temparature remained high and CPU usage was not extremely high, nor the temperature of Core 0.
I had to leave, so I left the system as it was for about 4.5 hours and on return found still a hanging system with too high temperatures and not excessive CPU-usage (from the scale of the graph - the actual values were off screen) about 40%.
I disconnected from mains (any other method to stop the system failed) and restarted. During the time to restart the computer the temperatures of core 0 had fallen to 67 C, core 1, 2, 3 had fallen to 60, 66, 65 and the temperature from sensor 2 to 55, composite to 50C.
Thereafter I did zypper dup, which resulted in sensor 2 heating to 79 C, CPU usage to 65%, Core 0 to 59C. After the zypper command finished all values dropped to usual levels.

I have no idea what to do further to diagnose the cause of the problem, especially because of the hours long using the system before the hang occurs due to high temperature.
Going away from KDE to XFCE would be possible, of course, but is very unsatisfactory.

Das ist mir ziemlich schnell auf gefallen. Darauf hin habe ich zweimal systemd-cgtop empfohlen. Du hast es zweimal ignoriert. Ich empfehle es zum dritten mal. Danach ist Schluss!

What repo did you get this from, and how long ago? Opi shows it in 3 different homes that I do not recognize.

I humbly apologise! Lack of knowledge/understanding hampered me in providing the requested information.
I now believe I understood, here is the output I just now generated:

**Lenovo-daan:~ #**** systemd-cgtop -1 --cpu=time user.slice/user-1000.slice/user@1000.service
****Control Group Tasks CPU Time Memory Input/s Output/s
user.slice/user-1000.slice/user@1000.service 1124 11min 5.878586s 13.3G - -
user.slice/user-1000.slice/user@1000.service/app.slice 933 5min 58.090080s 4.6G - -
user.slice/user-1000.slice/user@1000.service/session.slice 153 4min 57.186742s 7.8G - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service 32 3min 6.891726s 7.2G - -
user.slice/user-1000.slice/use…app.slice/app-firefox-ce567712254e417fac8fc0bdb7968a16.scope 279 2min 42.934933s 1.4G - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kwin_x11.service 28 1min 45.641787s 392.6M - -
user.slice/user-1000.slice/use…/app-google\x2dchrome-9f1366da3951443e83db128868017353.scope 175 1min 26.718153s 1016.1M - -
user.slice/user-1000.slice/use…slice/app-thunderbird-70141c24d9584231a467d4732171ad96.scope 176 1min 6.612191s 773.3M - -
user.slice/user-1000.slice/use…app.slice/app-psensor-990115fa9c7a4b578764e2b517ebf7f7.scope 7 23.487758s 14.4M - -
user.slice/user-1000.slice/use…0.service/app.slice/app-org.kde.kalendarac@autostart.service 219 10.100412s 736.1M - -
user.slice/user-1000.slice/user@1000.service/background.slice 36 10.010711s 910.9M - -
user.slice/user-1000.slice/user@1000.service/background.slice/kde-baloo.service 3 8.268518s 837.2M - -
user.slice/user-1000.slice/use…p.slice/app-konsolesu-849178eb91e8424fa333668edc8aeca4.scope 14 3.392584s 85.5M - -
user.slice/user-1000.slice/use…libreoffice\x2dwriter-0421aa84bf8a434b9ccd6b8aa7a98ac7.scope 17 1.783183s 351.6M - -
user.slice/user-1000.slice/user@1000.service/session.slice/dbus.service 18 1.654281s 54.1M - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kded.service 17 1.542892s 51.7M - -
user.slice/user-1000.slice/use…lice/app-org.kde.kpat-6d3c175f870248a8a74514d2ced71392.scope 7 954.163ms 119.5M - -
user.slice/user-1000.slice/use…ce/app-org.kde.kwrite-debdf39ba4224c4889ad00280048c725.scope 7 887.517ms 84.5M - -
user.slice/user-1000.slice/user@1000.service/init.scope 2 583.472ms 3.9M - -
user.slice/user-1000.slice/use…ce/app.slice/app-org.kde.kdeconnect.daemon@autostart.service 8 468.035ms 22.2M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-kglobalaccel.service 3 455.489ms 5.7M - -
user.slice/user-1000.slice/user@1000.service/app.slice/app-kaccess@autostart.service 7 398.919ms 18.5M - -
user.slice/user-1000.slice/user@1000.service/session.slice/at-spi-dbus-bus.service 8 332.778ms 5.8M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-powerdevil.service 6 325.302ms 8.3M - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-ksmserver.service 7 300.818ms 19.2M - -
user.slice/user-1000.slice/use…00.service/background.slice/plasma-kactivitymanagerd.service 6 280.266ms 25.2M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-polkit-agent.service 9 247.756ms 20.8M - -
user.slice/user-1000.slice/use….service/session.slice/plasma-xdg-desktop-portal-kde.service 7 245.243ms 18.8M - -
user.slice/user-1000.slice/user@1000.service/app.slice/xdg-desktop-portal-gtk.service 8 235.022ms 28.7M - -
user.slice/user-1000.slice/user@1000.service/session.slice/pulseaudio.service 7 162.411ms 22.7M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-kscreen.service 3 148.507ms 5.7M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-xembedsniproxy.service 3 146.348ms 3.8M - -
user.slice/user-1000.slice/use…0.service/background.slice/plasma-gmenudbusmenuproxy.service 3 138.521ms 3.9M - -
user.slice/user-1000.slice/user@1000.service/session.slice/xdg-desktop-portal.service 6 137.315ms 12.5M - -
user.slice/user-1000.slice/user@1000.service/session.slice/wireplumber.service 4 37.667ms 6.3M - -
user.slice/user-1000.slice/user@1000.service/session.slice/xdg-document-portal.service 7 33.045ms 6.0M - -
user.slice/user-1000.slice/user@1000.service/session.slice/gvfs-daemon.service 9 21.251ms 5.1M - -
user.slice/user-1000.slice/user@1000.service/session.slice/pipewire.service 3 18.511ms 2.1M - -
user.slice/user-1000.slice/use…ice/app.slice/app-geoclue\x2ddemo\x2dagent@autostart.service 3 9.271ms 2.9M - -
user.slice/user-1000.slice/user@1000.service/app.slice/dconf.service 3 5.786ms 852.0K - -
user.slice/user-1000.slice/user@1000.service/app.slice/xdg-permission-store.service 3 4.235ms 864.0K - -
**Lenovo-daan:~ #****

At this very moment the system is running KDE smoothly.
Psensor shows a very spiky graph with sensor 2 between 32 C and 48C, Core 0 between 30 C and 33 C. Each value remains the same for about 4 seconds max, then either goes up or down, hence the spiky graph.
Accessing Google Maps for a driving time gave a spike for sensor 2 to 52C, which, when doing nothing, slowly (20 seconds) dropped to 38 C; running zypper dup and updating 2 packages raised sensor 2 within 4 seconds to 61 C. After completion it took again about 20 seconds to return to a temperature below 40 C.
To me that suggests that Internet access may be involved, but I have not been able to intentionally overheat-and-hang using the Internet - even an zypper update with more than 500 items did not result in overheating (it remained at about 75 C max). In fact no intentional action resulted in overheating…

CPU times shown by systemd-cgtop are accumulated values since boot. Background slice is fine. Your session slice is quite bloated compared to the app slice. You may compare this to host erlangen:

Control Group                                                               Tasks         CPU Time   Memory  Input/s Output/s
user.slice/user-1000.slice/user@1000.service                                  852 45min 31.124302s     6.0G        -        -
**user.slice/user-1000.slice/user@1000.service/app.slice                        727 38min 46.098045s     4.2G        -        -**
user.slice/user-1000.sli…p-firefox-aa33bde8d27b4fb0a8320f7bbe9a5c5c.scope     464 11min 50.731530s     1.6G        -        -
**user.slice/user-1000.slice/user@1000.service/session.slice                     87  6min 30.210234s   633.8M        -        -**
user.slice/user-1000.sli…00.service/session.slice/plasma-kwin_x11.service      11  2min 15.925139s    69.5M        -        -
user.slice/user-1000.sli…e.konsole-c0dfcab078624964a4fa1dc6086f3ba9.scope      12  1min 45.291552s   621.8M        -        -
user.slice/user-1000.sli…000.service/session.slice/pipewire-pulse.service       2  1min 41.642313s    40.6M        -        -
user.slice/user-1000.sli…service/session.slice/plasma-plasmashell.service      16  1min 21.296919s   354.8M        -        -
user.slice/user-1000.sli…p.slice/app-org.kde.kalendarac@autostart.service     173  1min 18.876406s   738.6M        -        -
user.slice/user-1000.sli…user@1000.service/session.slice/pipewire.service       2   1min 1.284082s    27.0M        -        -
user.slice/user-1000.sli…de.kmail2-0ae46d759b6d436fa22896fca3474a9e.scope      52       39.422506s   505.2M        -        -
**user.slice/user-1000.slice/user@1000.service/background.slice                  36       14.388253s     1.2G        -        -**
user.slice/user-1000.sli…@1000.service/background.slice/kde-baloo.service       3        4.144321s     1.1G        -        -
user.slice/user-1000.sli…r@1000.service/session.slice/plasma-kded.service      15        4.087129s    48.7M        -        -
user.slice/user-1000.sli…ackground.slice/plasma-kactivitymanagerd.service       6        3.182326s    12.1M        -        -
user.slice/user-1000.sli…rvice/background.slice/plasma-powerdevil.service       6        2.856034s    10.1M        -        -
user.slice/user-1000.slice/user@1000.service/session.slice/dbus.service         1        2.237913s     2.3M        -        -
user.slice/user-1000.sli…0.service/session.slice/plasma-ksmserver.service       7        1.672282s    27.0M        -        -
user.slice/user-1000.sli…0.service/app.slice/save-jalbum-settings.service       2        1.309409s     1.5M        -        -
user.slice/user-1000.sli…ice/background.slice/plasma-kglobalaccel.service       3        1.082296s     7.1M        -        -
user.slice/user-1000.sli….service/app.slice/app-kaccess@autostart.service       7        981.768ms    16.8M        -        -
user.slice/user-1000.sli…r@1000.service/session.slice/wireplumber.service       4        873.325ms    15.2M        -        -
user.slice/user-1000.sli…ice/background.slice/plasma-polkit-agent.service       9        672.816ms    17.1M        -        -
user.slice/user-1000.sli….service/background.slice/plasma-kscreen.service       3        670.931ms     3.3M        -        -
user.slice/user-1000.sli…sion.slice/plasma-xdg-desktop-portal-kde.service       7        656.108ms    19.0M        -        -
user.slice/user-1000.sli…e/background.slice/plasma-xembedsniproxy.service       3        612.040ms     3.9M        -        -
user.slice/user-1000.sli…ckground.slice/plasma-gmenudbusmenuproxy.service       3        594.292ms     4.1M        -        -
user.slice/user-1000.sli…service/app.slice/xdg-desktop-portal-gtk.service       8        426.855ms    32.4M        -        -
user.slice/user-1000.slice/user@1000.service/init.scope                         2        425.093ms     3.5M        -        -
user.slice/user-1000.sli…service/session.slice/xdg-desktop-portal.service       6        403.473ms    15.0M        -        -
user.slice/user-1000.sli…ervice/session.slice/xdg-document-portal.service       7         38.607ms     2.5M        -        -
user.slice/user-1000.sli…r@1000.service/session.slice/gvfs-daemon.service       9         14.302ms     6.1M        -        -
user.slice/user-1000.sli…e/app-geoclue\x2ddemo\x2dagent@autostart.service       3          6.759ms     2.9M        -        -
user.slice/user-1000.slice/user@1000.service/app.slice/dconf.service            3          3.721ms   940.0K        -        -
user.slice/user-1000.sli…0.service/app.slice/xdg-permission-store.service       3          2.749ms   912.0K        -        -
erlangen:~ # 

To further investigate I suggest creating a new user and quitting from the current graphical login. Then login the new user to KDE and run the session until some 1h cpu time has accumulated. Post the new output.

Also post the details of session slice:

systemd-cgtop -1 --cpu=time user.slice/user-1000.slice/user@1000.service/session.slice
...
Control Group                                                                Tasks        CPU Time   Memory  Input/s Output/s
user.slice/user-1000.slice/user@1000.service/session.slice                      87 6min 36.562724s   633.8M        -        -
user.slice/user-1000.sli…000.service/session.slice/plasma-kwin_x11.service      11 2min 18.156188s    69.5M        -        -
user.slice/user-1000.sli…1000.service/session.slice/pipewire-pulse.service       2 1min 43.454606s    40.4M        -        -
user.slice/user-1000.sli….service/session.slice/plasma-plasmashell.service      16 1min 22.295667s   354.8M        -        -
user.slice/user-1000.sli…/user@1000.service/session.slice/pipewire.service       2  1min 2.426025s    27.0M        -        -
user.slice/user-1000.sli…er@1000.service/session.slice/plasma-kded.service      15       4.205625s    48.7M        -        -
user.slice/user-1000.slice/user@1000.service/session.slice/dbus.service          1       2.238238s     2.3M        -        -
user.slice/user-1000.sli…00.service/session.slice/plasma-ksmserver.service       7       1.697926s    27.0M        -        -
user.slice/user-1000.sli…er@1000.service/session.slice/wireplumber.service       4       873.370ms    15.2M        -        -
user.slice/user-1000.sli…ssion.slice/plasma-xdg-desktop-portal-kde.service       7       676.057ms    19.0M        -        -
user.slice/user-1000.sli….service/session.slice/xdg-desktop-portal.service       6       407.472ms    15.1M        -        -
user.slice/user-1000.sli…service/session.slice/xdg-document-portal.service       7        38.607ms     2.5M        -        -
user.slice/user-1000.sli…er@1000.service/session.slice/gvfs-daemon.service       9        14.302ms     6.1M        -        -
erlangen:~ # 

Just after I posted this reply, I had to go to a shop. This took me about half an hour, during which my computer was unattended (nobody home) and quietly doing whatever an idle computer is doing.
Upon return I saw the graph of Psensor with the usual spikes and a significant rise in temperature of sensor2 and composite. The temperature was 78 C. Inspection of the graph showed that the rise started 1 minute before my return and took about 15 seconds to go from 48 to 78 C. The system was slow, but did not hang,so I was able to again run the systemd-cgtop command with the following output:


Lenovo-daan:~ # systemd-cgtop -1 --cpu=time user.slice/user-1000.slice/user@1000.service
Control Group Tasks CPU Time Memory Input/s Output/s
user.slice/user-1000.slice/user@1000.service 1124 11min 5.878586s 13.3G - -
user.slice/user-1000.slice/user@1000.service/app.slice 933 5min 58.090080s 4.6G - -
user.slice/user-1000.slice/user@1000.service/session.slice 153 4min 57.186742s 7.8G - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service 32 3min 6.891726s 7.2G - -
user.slice/user-1000.slice/use…app.slice/app-firefox-ce567712254e417fac8fc0bdb7968a16.scope 279 2min 42.934933s 1.4G - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kwin_x11.service 28 1min 45.641787s 392.6M - -
user.slice/user-1000.slice/use…/app-google\x2dchrome-9f1366da3951443e83db128868017353.scope 175 1min 26.718153s 1016.1M - -
user.slice/user-1000.slice/use…slice/app-thunderbird-70141c24d9584231a467d4732171ad96.scope 176 1min 6.612191s 773.3M - -
user.slice/user-1000.slice/use…app.slice/app-psensor-990115fa9c7a4b578764e2b517ebf7f7.scope 7 23.487758s 14.4M - -
user.slice/user-1000.slice/use…0.service/app.slice/app-org.kde.kalendarac@autostart.service 219 10.100412s 736.1M - -
user.slice/user-1000.slice/user@1000.service/background.slice 36 10.010711s 910.9M - -
user.slice/user-1000.slice/user@1000.service/background.slice/kde-baloo.service 3 8.268518s 837.2M - -
user.slice/user-1000.slice/use…p.slice/app-konsolesu-849178eb91e8424fa333668edc8aeca4.scope 14 3.392584s 85.5M - -
user.slice/user-1000.slice/use…libreoffice\x2dwriter-0421aa84bf8a434b9ccd6b8aa7a98ac7.scope 17 1.783183s 351.6M - -
user.slice/user-1000.slice/user@1000.service/session.slice/dbus.service 18 1.654281s 54.1M - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kded.service 17 1.542892s 51.7M - -
user.slice/user-1000.slice/use…lice/app-org.kde.kpat-6d3c175f870248a8a74514d2ced71392.scope 7 954.163ms 119.5M - -
user.slice/user-1000.slice/use…ce/app-org.kde.kwrite-debdf39ba4224c4889ad00280048c725.scope 7 887.517ms 84.5M - -
user.slice/user-1000.slice/user@1000.service/init.scope 2 583.472ms 3.9M - -
user.slice/user-1000.slice/use…ce/app.slice/app-org.kde.kdeconnect.daemon@autostart.service 8 468.035ms 22.2M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-kglobalaccel.service 3 455.489ms 5.7M - -
user.slice/user-1000.slice/user@1000.service/app.slice/app-kaccess@autostart.service 7 398.919ms 18.5M - -
user.slice/user-1000.slice/user@1000.service/session.slice/at-spi-dbus-bus.service 8 332.778ms 5.8M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-powerdevil.service 6 325.302ms 8.3M - -
user.slice/user-1000.slice/user@1000.service/session.slice/plasma-ksmserver.service 7 300.818ms 19.2M - -
user.slice/user-1000.slice/use…00.service/background.slice/plasma-kactivitymanagerd.service 6 280.266ms 25.2M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-polkit-agent.service 9 247.756ms 20.8M - -
user.slice/user-1000.slice/use….service/session.slice/plasma-xdg-desktop-portal-kde.service 7 245.243ms 18.8M - -
user.slice/user-1000.slice/user@1000.service/app.slice/xdg-desktop-portal-gtk.service 8 235.022ms 28.7M - -
user.slice/user-1000.slice/user@1000.service/session.slice/pulseaudio.service 7 162.411ms 22.7M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-kscreen.service 3 148.507ms 5.7M - -
user.slice/user-1000.slice/user@1000.service/background.slice/plasma-xembedsniproxy.service 3 146.348ms 3.8M - -
user.slice/user-1000.slice/use…0.service/background.slice/plasma-gmenudbusmenuproxy.service 3 138.521ms 3.9M - -
user.slice/user-1000.slice/user@1000.service/session.slice/xdg-desktop-portal.service 6 137.315ms 12.5M - -
user.slice/user-1000.slice/user@1000.service/session.slice/wireplumber.service 4 37.667ms 6.3M - -
user.slice/user-1000.slice/user@1000.service/session.slice/xdg-document-portal.service 7 33.045ms 6.0M - -
user.slice/user-1000.slice/user@1000.service/session.slice/gvfs-daemon.service 9 21.251ms 5.1M - -
user.slice/user-1000.slice/user@1000.service/session.slice/pipewire.service 3 18.511ms 2.1M - -
user.slice/user-1000.slice/use…ice/app.slice/app-geoclue\x2ddemo\x2dagent@autostart.service 3 9.271ms 2.9M - -
user.slice/user-1000.slice/user@1000.service/app.slice/dconf.service 3 5.786ms 852.0K - -
user.slice/user-1000.slice/user@1000.service/app.slice/xdg-permission-store.service 3 4.235ms 864.0K - -
Lenovo-daan:~ #

Thereafter the temperature dropped to 38 C.
Does that clarify matters?

This was posted before reading your message about login another user. Will follow your suggestion

There is zero difference between two CPU stats which implies that whatever hogged CPU during this period was running outside of cgroup you have chosen.

As you suggested,I made another user, rebooted and collected two outputs:

Lenovo-daan:~ # systemd-cgtop -1 --cpu=time  user.slice/user-1001.slice/user@1001.service
Control Group                                                                           Tasks   CPU Time   Memory  Input/s Output/s
user.slice/user-1001.slice/user@1001.service                                              223 53.669202s     1.6G        -        -
user.slice/user-1001.slice/user@1001.service/app.slice                                     62 34.019155s   669.7M        -        -
user.slice/user-1001.slice/u…slice/app-psensor-e5b83ef8d6744bc894241688a4575fdb.scope       6 20.556161s    36.9M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice                                116 18.073260s   922.3M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-kwin_x11.service         16  6.815290s   193.2M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-plasmashell.service      24  5.548712s   504.6M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-ksmserver.service         7  3.872581s    28.1M        -        -
user.slice/user-1001.slice/user@1001.service/background.slice                              43  1.015736s    87.7M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-kded.service             15  839.616ms    53.4M        -        -
user.slice/user-1001.slice/u…ice/app-konsolesu-43ec787c9779447786c11ff8364fb3a3.scope      10  651.338ms    35.1M        -        -
user.slice/user-1001.slice/user@1001.service/init.scope                                     2  559.531ms     3.9M        -        -
user.slice/user-1001.slice/u…pp-org.kde.kwrite-b24431c3c0bf4fcdb7bdcd6f83372ec6.scope       7  540.626ms    43.9M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/dbus.service                     4  317.677ms     4.6M        -        -
user.slice/user-1001.slice/u…pp.slice/app-org.kde.kdeconnect.daemon@autostart.service       8  300.405ms    24.8M        -        -
user.slice/user-1001.slice/u…bin\x2fkalendarac-63e6e6985f7847b293c748bcb258eb8a.scope       7  190.689ms    20.6M        -        -
user.slice/user-1001.slice/u…@1001.service/background.slice/plasma-powerdevil.service       6  190.517ms     8.2M        -        -
user.slice/user-1001.slice/user@1001.service/app.slice/app-kaccess@autostart.service        7  183.128ms    20.9M        -        -
user.slice/user-1001.slice/user@1001.service/app.slice/xdg-desktop-portal-gtk.service       8  168.206ms    32.5M        -        -
user.slice/user-1001.slice/u…001.service/background.slice/plasma-polkit-agent.service       9  163.128ms    21.1M        -        -
user.slice/user-1001.slice/u…vice/session.slice/plasma-xdg-desktop-portal-kde.service       7  160.942ms    19.2M        -        -
user.slice/user-1001.slice/u…001.service/background.slice/plasma-kglobalaccel.service       3  157.104ms     5.6M        -        -
user.slice/user-1001.slice/user@1001.service/background.slice/kde-baloo.service             3  134.406ms    11.0M        -        -
user.slice/user-1001.slice/u…1001.service/background.slice/plasma-baloorunner.service       7  126.796ms    18.6M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/pulseaudio.service               6  110.025ms    62.9M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/xdg-desktop-portal.service       6  102.791ms    23.5M        -        -
user.slice/user-1001.slice/u…ervice/background.slice/plasma-kactivitymanagerd.service       6   92.604ms     9.3M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/at-spi-dbus-bus.service          8   67.571ms     5.5M        -        -
user.slice/user-1001.slice/user@1001.service/background.slice/plasma-kscreen.service        3   52.600ms     3.7M        -        -
user.slice/user-1001.slice/u…1.service/background.slice/plasma-xembedsniproxy.service       3   50.672ms     3.8M        -        -
user.slice/user-1001.slice/u…rvice/background.slice/plasma-gmenudbusmenuproxy.service       3   47.905ms     5.9M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/wireplumber.service              4   38.444ms     7.4M        -        -
user.slice/user-1001.slice/u…r@1001.service/session.slice/xdg-document-portal.service       7   23.333ms     6.0M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/gvfs-daemon.service              9   16.936ms     9.2M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/pipewire.service                 3   15.852ms     2.1M        -        -
user.slice/user-1001.slice/u…app.slice/app-geoclue\x2ddemo\x2dagent@autostart.service       3   10.122ms     2.9M        -        -
Lenovo-daan:~ #

and also

Lenovo-daan:~ # systemd-cgtop -1 --cpu=time user.slice/user-1001.slice/user@1001.service/session.slice
Control Group                                                                            Tasks  CPU Time   Memory  Input/s Output/s
user.slice/user-1001.slice/user@1001.service/session.slice                                 112 5.521662s   617.4M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-plasmashell.service       20 2.733494s   336.6M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-kwin_x11.service          16 1.262301s   170.3M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-kded.service              15 545.260ms    30.1M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/dbus.service                      4 206.873ms     6.5M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/plasma-ksmserver.service          7 188.113ms    20.1M        -        -
user.slice/user-1001.slice/u…rvice/session.slice/plasma-xdg-desktop-portal-kde.service       7 156.108ms    20.5M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/pulseaudio.service                6  98.847ms     7.7M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/xdg-desktop-portal.service        6  58.376ms     4.9M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/at-spi-dbus-bus.service           8  39.927ms     5.0M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/wireplumber.service               4  32.416ms     3.3M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/xdg-document-portal.service       7  20.938ms     5.4M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/gvfs-daemon.service               9  15.688ms     4.3M        -        -
user.slice/user-1001.slice/user@1001.service/session.slice/pipewire.service                  3  15.261ms     1.8M        -        -
Lenovo-daan:~ #

For today my available time is up - other requests for my time are presented- , comparison of your output to mine I cannot do today anymore, will continue tomorrow.

Nope. You said “Tumbleweed overheats in KDE but not in XFCE”. Thus I suggested to watch [noparse]user@1000.service[/noparse]. However nothing happened in this control group. You need to search all groups for activities:

**erlangen:/sys/fs/cgroup #** find -name '*.slice' 
./user.slice 
./user.slice/user-1001.slice 
./user.slice/user-1001.slice/user@1001.service/session.slice 
./user.slice/user-1001.slice/user@1001.service/background.slice 
./user.slice/user-1001.slice/user@1001.service/app.slice 
./user.slice/user-1000.slice 
./user.slice/user-1000.slice/user@1000.service/session.slice 
./user.slice/user-1000.slice/user@1000.service/background.slice 
./user.slice/user-1000.slice/user@1000.service/app.slice 
./system.slice 
./system.slice/system-modprobe.slice 
./system.slice/system-getty.slice 
**erlangen:/sys/fs/cgroup #**

Start with “systemd-cgtop -1 --cpu=time”:

Control Group                                                            Tasks            CPU Time   Memory  Input/s Output/s
/                                                                         1590 1h 10min 23.130000s     8.5G        -        - 
user.slice                                                                1289   1h 5min 5.176945s     8.8G        -        - 
user.slice/user-1000.slice                                                 901  1h 3min 20.154786s     6.8G        -        - 
user.slice/user-1000.slice/user@1000.service                               893  1h 3min 19.057550s     6.8G        -        - 
system.slice                                                                63     5min 51.638914s     5.8G        -        - 
system.slice/display-manager.service                                        17     4min 18.641788s        -        -        - 
user.slice/user-1001.slice                                                 388     1min 42.976913s     1.6G        -        - 
user.slice/user-1001.slice/user@1001.service                               383     1min 41.693253s     1.5G        -        - 
system.slice/fetchmail.service                                               1          27.579438s        -        -        - 
system.slice/systemd-udevd.service                                           1           6.059141s        -        -        - 
system.slice/dbus.service                                                    1           5.832231s        -        -        - 
system.slice/upower.service                                                  3           4.824582s        -        -        - 
system.slice/sshd.service                                                    1           4.465981s        -        -        - 
system.slice/udisks2.service                                                 5           4.246856s        -        -        - 
init.scope                                                                   1           3.118190s     8.2M        -        - 
system.slice/irqbalance.service                                              2           1.884318s        -        -        - 
system.slice/postfix.service                                                 4           1.459513s        -        -        - 
system.slice/minidlna.service                                                2           1.281937s        -        -        - 
user.slice/user-1001.slice/session-8.scope                                   5           1.280044s    33.7M        -        - 
system.slice/apache2.service                                                 6           1.275774s        -        -        - 
system.slice/cups.service                                                    2           1.137303s        -        -        - 
user.slice/user-1000.slice/session-3.scope                                   8           1.093066s    32.9M        -        - 
system.slice/systemd-journald.service                                        1           745.700ms        -        -        - 
system.slice/polkit.service                                                  3           598.497ms        -        -        - 
system.slice/systemd-logind.service                                          1           488.411ms        -        -        - 
system.slice/rtkit-daemon.service                                            3           458.691ms        -        -        - 
system.slice/chronyd.service                                                 1            82.540ms        -        -        - 
system.slice/systemd-networkd.service                                        1            71.935ms        -        -        - 
system.slice/systemd-resolved.service                                        1            69.276ms        -        -        - 
system.slice/cron.service                                                    1            61.949ms        -        -        - 
system.slice/auditd.service                                                  2            46.243ms        -        -        - 
system.slice/system-getty.slice                                              1            43.953ms        -        -        - 
system.slice/system-getty.slice/getty@tty1.service                           1            43.953ms        -        -        - 
system.slice/rpcbind.service                                                 1            41.744ms        -        -        - 
system.slice/rsyncd.service                                                  1            23.528ms        -        -        - 
system.slice/mcelog.service                                                  1             6.049ms        -        -        - 
**erlangen:/sys/fs/cgroup #** 

Track down to the group which hogs the cpu time. It’s a few steps only. Post the results.