I have had a problem with artifacts when using my Nvidia GTS 250. I bought an HD 5770 and had no problems with artifacts (there were a whole host of new problems though so I ended up sending it back).
I RMA'd my old GTS 250 several weeks ago and the new card had the same problem. I hadn't thought to check the serial number on the new card but it had the same problem. I RMA'd that card just last week for the same reason and the new card arrived. I checked the serial number on this one and it is different. That was on a sticker stuck to the bottom of the card though so if it is somewhere else on the card I would like to know where.
However, in the absence of a second place to check for the serial number I would like to know what else could possibly cause artifacts. From bad CPU to bad mobo to bad RAM, anything other than the graphics card that could cause it I want to know.
You know, I just realized, the card I just got back came in a static bag that was too short for it. It wasn't completely covered. Those f-ing amateurs! I swear, they better send me a card in a retail box next time, unopened.
Also, in the interest of thorough troubleshooting, if anyone else knows of a component other than the graphics card that can cause artifacts, please post them here, I would like to check every avenue that I can.
You state you have been running both Nvidia and ATI cards on your system, did you completely remove all previous drivers before installing a new card, if not, download Driver Sweeper and the newest drivers for your current card. Uninstall drivers for your current card, boot to safemode and run Driver Sweeper and clean out any leftover drivers from previous installations.
Boot to normal Windows and install the newest drivers for your card.
This might sound like a dumb suggestion, but do the artifiacts appear on any monitor you hook it too. I was using a GT220 lying around waiting for my GTX470 to come and it gave me artifacts on an old dell 1024x1240 LCD, but not on my families 1650x1050 screen. The dell worked fine when I put the 470 in, and I am not sure how the 220 might act if I hooked if up to my new 1920x1080 monitor, but I can tell you the results if they are significant tonight.
I'm not really sure what this all means, but I would guess it means something is up with the video card, but I don't really know.
Ok, while it is always a good suggestion to rule out the stupid obvious possibilities before moving on the the hard to fix possibilities, it doesn't matter. I have replaced my nvidia card with an old, OLD ATI x600 and while it gets about 0-1 fps in furmark, there are no artifacts.
So I know it isn't the display since 1) it only happens during strenuous operations and 2) it only happens with the Nvidia card.
I have just called tech support for the gts 250 and showed them the screen shots of the artifacts (viewable through the links above) and they have promised to upgrade my card to a newer and/or better card. I might sell that card and get an EVGA card or something. It depends on what card they give me.
Thank you guys for the help. Hunter, have a gold medal shaped cookie.