I'm trying to diagnose a problem with my graphics card (I think). My specs are:
Power supply: Antec Neo Eco 620C
Mobo: ASRock Z77 Pro-4 M
Ram: 2x4GB Gskill
GPU: Gigabyte Radeon HD 6850, drivers 12.8.
CPU: Intel i3 2120
OS: Windows 7 64 Bit Ultimate
What I get is basically completely random crashes (the computer can run for days before anything happens or sometimes only 10 minutes before it crashes). They differ - sometimes BSODs (they usually say 'Hardware Malfunction', sometimes crashes with restart, screen freezes, but more commonly it is either a grey/black screen with horizontal fragmenting. In cases where it freezes or gives strange lines, I will often get a loud buzzing sound (from my speakers/headset).
It is not temp, everything is running at <40 degrees.
That is hardware, meaning that your gpu and / or memory on the gfx card might be O.K. When you do RAM test, you only test RAM that you installed in your PC but your gfx card also has RAM on it which you cannot test with memtest.
If you search this forum, you will see that I have the same series gfx card MSI R6850 Cyclone and I have had similar problems. Tech people at MSI advised me to update gfx card BIOS which I did and the new BIOS increased memory clock rate to a constant value at 1100 MHz, which was my full throttle memory clock. If you noticed these cards have different clock rates for both core and memory for different states the card is in, such as idle state, power state and other states in between.