8800 GTS + AA = Stutter ?

[Maplassie_GTR]

Hi.

I have massive lag specially when entering rooms, with projected lights (like that last door you go through and the light shines through, or the lights that shine out from the "outside" into a room) but only when I have AA enabled. I know the game is a resource hog on high settings, but when I whip out my 8800 and slap in my 2 old 7800 GTX cards in sli, I dont have that stutter/ lag. Wich to me sounds like a driver issue, but I went through the usual proceedings of uninstalling, reinstalling newer/older/beta/optimized drivers, and all the other usual stuff.

The lag is not ONLY in those scenarios, it's all round actually, but most noticable in those areas. Sometimes when close to a dog, it drops to 3 FPS ( I use fraps to check) Wich still is weird because my machine is more than strong enough to handle all the latest titles.
I also tried to se t my AA in my Nvidia control panel to "off" and only on ingame, and had the same issue. I also tried setting the AA option in the Nvidia Control panel to "enhance Application setting" and it does exactly the same.
Also it does not matter at all what settings I am running in the game (motion blur, noise filter etc) even If I set the resolution all the way down to 800x600 I get the same thing.

Hardware:

AMD 4800X2 (clocked at 2800MHZ)
2 GIG Kingston Hyper-X DDR466
XFX 8800 GTS 640MB
(works fine as I said before on my 2x7800 GTX cards)

Has anyone else experienced any 8800 Related slowdowns/lag?