28 November 2005 in General | Comments enabled

A few months back I got around to buying an nVidia 6800 graphics card. It is a reasonably performant card and should have all the bells and whistles to ensure most games run pretty well. I started off using it without any problems – mostly on older games that hadn’t run too smoothly on my old Radeon 9600 card (Sim City 4 etc).

However, over time I started trying some of the newer games like FarCry, Serious Sam II, Age of Empires 3. I was totally unimpressed at the problems that cropped up. Games like FarCry would run well for maybe 10 minutes and then start to get artifacts and become unplayable. Even more modern games like Age Of Empires 3 would actually hard lock my machine before I could even get into the game. Considering how much I paid for the card I was really unhappy.

My real challenge was that I don’t want to try and return the card and not be able to prove it’s broken – as it does work for most older games.

First off I tried the obvious – different versions of drivers. What I found when I tried to upgrade to the newest version drivers was that my system hard-locked as soon as windows loaded. Not such a good thing. Some reading showed that the latest drivers have serious issues…. with dual core systems – which I don’t have. So I went back to some older drivers so I could at least use Windows.

So I guessed that perhaps the card was overheating. I used the tools that came with my card to check the temperature, it sat around 40 degrees celcius and would go up to around 55 once games were cranking. From what I read this wasn’t too bad for a modern graphics card.

My next theory was that it could be a power issue. These modern surfboard sized graphics cards have their own molex connector to really suck the power down. The monitoring tool that came with the card reported voltages looked about right. They did fluctuate slightly when games ran. The problems continued even when I unplugged all unneeded components (DVD drive, second harddisk etc).

So I went and acquired a new computer case – a reasonably nice Thermaltake case with a lot more cooling and a beefed up power supply (430W). The voltages still varied slightly but I I can now rule that out as being the issue. Also the card now runs about another 5 degrees cooler which is great. Unfortunately the problems persisted.

After a while I started to think about what the games that failed had in common. My older games ran fine. So I figured that most newer games utilise pixel shaders. They’re a fancy new way of programmatically getting the graphics card to do some cool rendering (it’s what makes fancy new graphics so fancy I guess you could say). There is a lot happening in this space and it’s not going to go away. As a side note we’re now up to Shader Model 3.0 (SM 3.0) – according to nVidia my card should support everything up to and including 3.0.

Sure enough, in some of these games I can downgrade the version of the shaders used (or turn them off completely). Doing so makes the games run a lot better – no artifacts or hard locking. My next challenge was getting some hard proof that the card had defective shaders. After doing some hunting on Google I discovered a cool application from Microsoft called Display Compatibility Test Kit (DCT). DCT is the application that hardware vendors can use to test their hardware to ensure that it meets WHQL requirements. 107MB later and it was downloaded onto my machine.

A word of warning for anybody looking to run DCT – If you run all the tests included in the DCT application it can take around 36 hours to complete the testing!

I dug around and found the tests relating to pixel shaders, kicked them off and went to bed. I’ve attached this picture showing what happened (the normal windows logo means it ran successfully, the ones with a red cross are ones that failed). My understanding is that my card should have passed all of these.

DCT Shader Fail

I thought I had found some concrete proof of problems. Unfortunately things get a whole lot more murky when I realised that despite nVidia getting WHQL certified by Microsoft their newest cards actually fail the DCT tests (which they are supposed to pass). I still believe that my results are based on damaged pipelines – I actually got up at one point in the night and checked on it (yes – I’m that much of a geek :-) ) and watched some of the tests, sure enough, on the ones that failed they actually show the same corruption (mostly red dots).

If anybody out there actually feels like going to the great length of downloading DCT and running the shader tests on their 6800 and showing me how they faired I’d be pretty stoked :-) At this point I’m going to go old school and just take some digital photos of my computer with the corruption and hope that it will be enough to get a new card. I don’t think they would have too many problems with me getting a replacement but on the off chance I get somebody who wants to actually test it a lot to prove the fault I want to be armed with all the facts I can.

- JD

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2 comments. Add your own comment.

James says 15 June 2006 @ 20:27

I have exactly the same problem and i got mine replaced and it still did it. Mine seems to do it with C&C generals, Fear and CSS. But odly not doom 3

And ive ive done half of what youve done, new power, more air flow and different drivers

I’ll give that program a try and see if it comes up with the same results and post them for you if thats any help. :)

traskjd says 15 June 2006 @ 22:21

Interesting, thanks for leaving a comment. Perhaps you just had bad luck and got two broken ones?

In a later blog post I got my card replaced and it has worked ever since :) Hope you get yours sorted :)

– JD

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