Hello,

I have a problem with my video card. Whenever I run a DirectX 10 game, it works for a few seconds (10 or so) and then starts displaying nothing but big polygons.

I have tested this with Crysis and Resident Evil 5, both have the same problems. The same games running under DirectX 9 work fine, except for some small black squares once in a while.

I have the following specs:

Asus P7P55D LE
Intel Core i5 750
Sapphire Radeon HD4850 1GB
2x2GB Patriot Viper II Sector 5, DDR3 1600 MHz
OCZ Stealth X Stream 500SXS 500W

At first I thought it could be the video card overheating (it has stock cooling), but the game crashes even when it's running at 50 degrees C, and it's never been higher than 70.

I also thought it could be the PSU, but as far as I know 500W is enough for this computer, especially because I haven't overclocked anything.

My OS is Windows 7 X64 and I am using Catalyst 10.10, but I have also tried many older versions with no success.

I don't think there is a problem with the card itself, or else it wouldn't run DirectX 9 games I believe.

I have spent many hours searching for a solution but I couldn't, so any help is appreciated.

Thank you.

EDIT:

I did some further investigation about the problem, and it seems taspeotis was right, it might be related to memory.

I slightly underclocked the memory from 993 to 965 MHz and the problem went away completely. Both the black squares using DirectX 9 and the weird polygons using DirectX 10.

I was using RE DirectX 10 Benchmark, as it consistently crashed around the same point, and now I can play the full benchmark with no artifacts at all.

Unfortunately, the underclock has an obvious hit in performance. Although it's not critical, it's definitely noticeable.

So, if the video memory test software showed no erros, but the card needs an underclock to work, what might be the problem? Temperature? Voltage?

By the way, I couldn't find what the default voltage for this card is. And what is a good software to try and increase it? I tried Ati Tray Tools but it has a bug that increases the clock speed dramatically whenever I change something in the Overclock tab, so I'm afraid it might fry my card.

Worst case scenario, if I don't find I solution I will try to slightly increase the GPU clock to compensate for the memory clock.

Thank you again.