IIt works, sort of. EVGA 8800 512 & Gainward 8800 1gb.
I can restart BSOD free if i disable sli before restart or shutdown.
Strange thing is the first time i dit this and afther that tried another restart with sli enabled and it worked! Then tried connecting SLI bridge, that screwed up the BSOD free rebooting...
Restarted procedure. And can reproduce. Will try now if i can trick it again and keep rebooting with it enabled after doing the on off trick.
If not always turning it on and of seems a good enough for me work arround to to enjoy the sli speeds
EDIT: It works but i'm unalbe to use the sli bridge. (I think it doesn't matter much because the 2x8800 are on a GB 990FX with 16x and 8x pci express) For extra stability i turn windows composition of and turn sli on and of everytime i want to game or restart also should turn of sleep, one time it resumed good. The other time it hanged and screwed up stable reboot.
So with a liddle fiddling i got it working an rock stable. allready played different games for e few hours. So looks good!
Again all the internets to OP !
EDIT2: Tried switching cards around. Gave more stability WITH bridge on at desktop. But gave artifacts and crash in games.
For some reasing afther all this playing arround i'm able to leave sli on and reboot.
Slot 1: EVGA 8800GT
512mb
Slot 2: Gainward 8800GT
1024mb
Performance is insane