ok, so ive never had to seek help with a config problem before but I can't figure this one out...

HP XW9300 Workstation :

Vista Ultimate 32bit
Tyan K8WE Thunder MoBo
Dual Opteron 250s (64bit 2.4Ghz)
4 gigs ECC reg PC3200
2x EVGA 8800GS Superclocked
750w Delta PSU
150gb SCSI raid 0
750gb SATA single
Memorex dvd/cd burner
Linksys 802.11g


As I understand it this is just about the best setup for sli as the K8WE dedicates 2 gigs and one card over a true 16x bus to each proc.

The scsi array, mobo, psu and 2 gigs of the ram are original, everything else was added by me, all installations went smoothly and the system is as stable as can be, the problem is that my fps in any game i try is 1/3 higher with sli disabled.

I have tried 3 different sli bridges, swapped gfx card slots and even traded out the cards one at a time at frys. I've tried the 175.16 and .19 drivers as well as a few archived ones for good measure, reflashed the bios several times, and tried every pcie connector on my psu (there are 4). The last step was to disconnect unneeded harware one at a time to make sure it wasn't a power issue, got all the way down to mobo, 1 hdd, procs, ram, and gfx and the issue persisted. The best part is that my original cards (2x quadro FX3400) worked and still work just fine in SLI, gaining close to a 100% increase in fps every time sli is enabled... which is about 10fps higher than one properly functioning 8800 in most applications.

Anyway, I'm fresh out of ideas... any help would be greatly appreciated.

update: used driver and cab cleaners between uninstalls to no effect and then did a full format and fresh install of vista over the weekend...

3400's still work, 8800's still don't... wtf!