It seems to be a problem with the card and Vista/7. Not all 7900 series cards are effected but in the weeks I've been researching the issue it seems the 7900 series are the only ones that this glitch occurs with.
I've tried every
driver as far back as 15x.xx-190, and no luck. Although the older
drivers cause the issue to happen much less frequently, my best luck has been with the 156
drivers (I think its the 156
drivers, not entirely sure off the top of my head). The problem only occurs for a few seconds when a video is opened, however, anything that is heavily graphics dependent (Milkdrop 2.0 for example) will cause the problem for as long as it runs.
Rivatuner shows a spike in the core speeds across the board of about a 50-100mghz jump, once the speeds go back down, video returns to normal. The newer drivers cause this clock jump a lot more frequently under Vista and 7, but not XP.
My card is an EVGA, and the problem seems to be most common with that brand, though I can't say with any certainty that in researching the issue other cards might have the same issue.
Rolling back to older drivers makes it bearable, but I hate having a computer that isn't running at 100%. Win 7 is such a nice OS though that I will deal with it.
I tried posting on the EVGA forums, and contacted EVGA, but no response. This seems to be a fringe problem with the 7900 series that Nvidia in general has decided to ignore. It seems the best solution for the problem is to switch to ATI.
EDIT: Also, a search of these forums using 7900GT will bring quite a list of people dealing with the same problem with links to temp fixes for this issue, as it's been around apparently since 2007.
http://forums.nvidia.com/index.php?s...00%20gto&st=40