I had a XFX 6600GT that brand new would look exactly like that screen shot within minutes of playing. I can't find them, but had loads of Farcry and 3dmark screenies that would look all too familiar to you. I RMA'd the card.
Unreleated, but I stayed away from 7900GT's when they first came out as they had alot of burning issues back then. Litterally hundreds of them on evga's forums in a talley thread. Also, XFX closed their forums down at that time, which I don't believe was coincidence.
I don't think this ever been confirmed, but its the best explanation I've heard of.
The 7900GT was simply overclocked to high. The memory they used in those cards was a bad choice. If you have a factory overclocked 7900GT, bring the memory back down to where the stock cards are. (you can leave the core overclock alone.) Many 7900GT's died because the memory clocks were simply to high for those used. (it might have been a cooling issue.) I switched from an NF4 + 7900GT to an Express 200 + x1800XT because of this issue.
Problem is that this happens very rarely, in painkiller in some levels only, tf2 happens and gets worse only when it chooses to, and 3dmark 2006 somedays the textures get jerky, but even that is rare, and i know how will they treat my problem "we are sorry but we have not encontered any problem whatsoever..".
I printed a few of the screenshots from different games and stuck in the box with my RMA just in case. i was worried they would test it for a few seconds and say it's fine, when it took a few minutes to freak out like that. They gave me no problems exchanging my card.
I owned an MSI 7900gt that did very similar things, as well as crashing 3dmark06 (in the same spot everytime) as well as many games would crash. Upgraded to a 1900xtx, no more crashing!, however I am now back with nvidia (XFX 8800gt) which runs flawless btw.