How to know if i've cooked my graphics card

I am running openSUSE 12.3 Tumbleweed 64 bit.

My laptop (Dell Vostro 3350) has a (painful) hybrid graphics set up i915/AMD Radeon HD 6400M.

It has never been much fun to get functioning and i’ve usually just switched off the discrete card with switcheroo. Recently i’ve installed the AMD Catalyst Drivers using the makerpm script by Sebastian Siebert - Sebastian Siebert | Linux, openSUSE, Software und was noch interessant ist. At least this allows me to switch to the discrete card and get a better graphics performance.

However i have an external monitor (Dell U2412m) which i connect via HDMI plugged into a dual dvi connector (no HDMI input on monitor). In the past i’ve had troubles with driver instability leading to random flicking between the laptop and the display. Usually i could get it to settle into a particular configuration by doing a few tricks. Now when i plug my laptop in, it is just crazily throwing between each display and flashing on and off from each screen. It has made my external display un-useable. Note i have tried with other laptops running Linux and my monitor works fine. I also have replicated the same problem with Linux Mint on this machine, so we can exclude it being a problem specific to openSUSE.

I am starting to suspect that the AMD graphics card on my machine is actually broken and needs replacing. My laptop is still under warranty, but i’ll have to convince them because i am not running Windoze.

So i am looking for help in diagnosing this problem further.

Here is some specs:

# uname -r
# lspci -vnn


00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
        Subsystem: Dell Device [1028:04cc]
        Flags: bus master, fast devsel, latency 0, IRQ 51
        Memory at f6400000 (64-bit, non-prefetchable) [size=4]
        Memory at d0000000 (64-bit, prefetchable) [size=256]
        I/O ports at f000 [size=64]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [d0] Power Management version 2
        Capabilities: [a4] PCI Advanced Features
        Kernel driver in use: i915

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Caicos [Radeon HD 6400M/7400M Series] [1002:6760] (rev ff) (prog-if ff)
        !!! Unknown header type 7f
        Kernel driver in use: fglrx_pci

FGLRX driver is AMD Catalyst 13.8 Beta.[/size][/size][/size]