As long as I've had this computer, I've experienced video artifacts and crashes when playing games. I initially put the blame on the games (Oblivion and Fallout 3), as I have experienced problems with these games on other computers in the past. When I started playing other games (World of Warcraft, Splinter Cell: Chaos Theory, Thief: Deadly Shadows, etc.), however, I started having the same issues, and decided to contact Sapphire about the video card I was using at the time (Radeon 4890.) I ended up RMAing that card, but had the same problem with the new one I received.
I have since tried a brand new card (Radeon 5850), and an older card (Radeon 3870), and experience the same issue with both of those cards. Additionally, I have run all three cards in a different computer with no issues. I have completely removed old drivers each time I have swapped video cards, and have also tried with and without the onboard video enabled. I have tried cards in both PCI-E slots on the motherboard, but have the same issue in both. I have done no overclocking of any kind. I have monitored CPU and Video Card temperatures while playing games and neither exceeds 65°C. I get artifacts even when running the games on their lowest settings.
I have tried swapping the power supply in the problem computer with the power supply that I knew ran the cards successfully in the second computer, but still had the same issue with the problem computer.
I have updated the motherboard BIOS three times since building the computer. The only time that games have ever run without issue for me is when I use only the onboard video, but this is obviously limiting.
You have pretty much ruled out everything but the motherboard!
All the cards work in different computers and working power supply from a different computer that ran the cards fine does not solve the problem in yours.
Replace the motherboard!
That's what I was afraid of, sadly. I actually sent a support request to ASUS at the same time I posted this. I just thought I'd see if someone more knowledgeable than I had some other suggestions while I waited lord knows how long for their reply. Thanks for your reply!