Memory clarification

I’m upgrading an old Dell Inspiron with a new ssd. When I opened the box, I saw an empty memory bank. I don’t understand enough about ram to get a proper fill for that bank. The current memory is an

SKhynix 8GB 1Rx8 PC4-2400T-UA1-11

I assume this is 2400 Mhz, but most replacements offered are 19200. Also, they are listed as DDR4. Does PC4 equal DDR4? What memory is compatible? I remember that memory has to match, but how much?

Yes they are all different ways of saying the same thing pc4-19200 is also DDR4-2400

link to ebay with the same memory title of the sale

SK hynix 8GB PC4-19200 (DDR4-2400) SO-DIMM Memory Module (HMA81GS6AFR8N-UH)

To get all the relevant information run (as root user);

dmidecode -t memory

Anything using DDR4 can’t be all that old. Inspiron is a desktop or tower, not a laptop, right?

When I opened the box, I saw an empty memory bank. I don’t understand enough about ram to get a proper fill for that bank…I remember that memory has to match, but how much?
Non-laptop (conventional) PCs of your vintage usually support dual channel RAM. That means maximum performance comes from a well matched pair of RAM sticks. That means both are same size as well as have same timing characteristics. The difference between 1 stick and 2 has approached a 90% improvement in some cases I’ve observed.

Replacing the HDD by a SSD and adding 8GB will make the Dell Inspiron fly.

Don’t assume anything. Provide evidence. It’s easy and doesn’t hurt:

**3400G:~ #** inxi -zFm           
**System:    Kernel:** 5.12.3-1-default x86_64 **bits:** 64 **Console:** tty pts/1 **Distro:** openSUSE Tumbleweed 20210515  
**Machine:   Type:** Desktop **Mobo:** ASUSTeK **model:** PRIME B450-PLUS **v:** Rev X.0x **serial:** <filter> **UEFI:** American Megatrends **v:** 2409  
           **date:** 12/02/2020  
**Memory:    RAM:****total:** 29.27 GiB **used:** 3.53 GiB (12.1%)  
           **Array-1:****capacity:** 128 GiB **slots:** 4 **EC:** None  
           **Device-1:** DIMM_A1 **size:** No Module Installed  
           **Device-2:** DIMM_A2 **size:** 16 GiB **speed:** 2133 MT/s  
           **Device-3:** DIMM_B1 **size:** No Module Installed  
           **Device-4:** DIMM_B2 **size:** 16 GiB **speed:** 2133 MT/s  
**CPU:       Info:** Quad Core **model:** AMD Ryzen 5 3400G with Radeon Vega Graphics **bits:** 64 **type:** MT MCP **cache:****L2:** 2 MiB  
           **Speed:** 1256 MHz **min/max:** 1400/3700 MHz **Core speeds (MHz):****1:** 1256 **2:** 1256 **3:** 1256 **4:** 1283 **5:** 1260 **6:** 1258 **7:** 1359  
           **8:** 1258  
**Graphics:  Device-1:** Advanced Micro Devices [AMD/ATI] Picasso **driver:** amdgpu **v:** kernel  
           **Display:****server:** X.Org 1.20.11 **driver:****loaded:** amdgpu,ati **unloaded:** fbdev,modesetting,vesa  
           **resolution:** 1920x1200~60Hz  
           **OpenGL:****renderer:** AMD Radeon Vega 11 Graphics (RAVEN DRM 3.40.0 5.12.3-1-default LLVM 12.0.0) **v:** 4.6 Mesa 21.1.0  
**Audio:     Device-1:** Advanced Micro Devices [AMD/ATI] Raven/Raven2/Fenghuang HDMI/DP Audio **driver:** snd_hda_intel  
           **Device-2:** Advanced Micro Devices [AMD] Family 17h HD Audio **driver:** snd_hda_intel  
           **Sound Server-1:** ALSA **v:** k5.12.3-1-default **running:** yes  
           **Sound Server-2:** PulseAudio **v:** 14.2-rebootstrapped **running:** yes  
**Network:   Device-1:** Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet **driver:** r8169  
           **IF:** eth0 **state:** down **mac:** <filter>  
           **Device-2:** Qualcomm Atheros AR9287 Wireless Network Adapter **driver:** ath9k  
           **IF:** wlan0 **state:** up **mac:** <filter>  
**Drives:    Local Storage:****total:** 2.5 TiB **used:** 1.81 TiB (72.4%)  
           **ID-1:** /dev/sda **vendor:** Seagate **model:** ST2000DM001-1CH164 **size:** 1.82 TiB  
           **ID-2:** /dev/sdb **vendor:** Samsung **model:** SSD 850 EVO 500GB **size:** 465.76 GiB  
           **ID-3:** /dev/sdc **vendor:** Samsung **model:** SSD 850 EVO 250GB **size:** 232.89 GiB  
**Partition: ID-1:** / **size:** 40 GiB **used:** 26.76 GiB (66.9%) **fs:** btrfs **dev:** /dev/sdc3  
           **ID-2:** /boot/efi **size:** 99.8 MiB **used:** 31.3 MiB (31.4%) **fs:** vfat **dev:** /dev/sdc1  
           **ID-3:** /home **size:** 427.82 GiB **used:** 354.64 GiB (82.9%) **fs:** ext4 **dev:** /dev/sdb3  
           **ID-4:** /opt **size:** 40 GiB **used:** 26.76 GiB (66.9%) **fs:** btrfs **dev:** /dev/sdc3  
           **ID-5:** /var **size:** 40 GiB **used:** 26.76 GiB (66.9%) **fs:** btrfs **dev:** /dev/sdc3  
**Swap:      Alert:** No Swap data was found.  
**Sensors:   System Temperatures:****cpu:** 39.8 C **mobo:** N/A **gpu:** amdgpu **temp:** 39.0 C  
           **Fan Speeds (RPM):** N/A  
**Info:      Processes:** 289 **Uptime:** 11:21:43  up 1 day  5:53,  4 users,  load average: 0.48, 0.62, 0.48 **Shell:** Bash **inxi:** 3.3.03  
**3400G:~ #**