ASUS P5N-T Deluxe, 8800GT Problem

Running an E8400. Between 1550 and 1600 FSB, Windows 7 comes up in 800x600. It's set to 1680x1050. PCI freqs fixed at default 100MHz.

Only voltages I've changed are vCore and vTT (1.3V). Prior to setting vTT, Windows would not start at all above 1550. Now it starts, but the video mode is screwy.

The 8800GT is a factory overclocked "BFG" generic from Best Buy a couple of years ago. Never had a problem with it. Obviously, I'm hoping to upgrade the CPU without affecting the PCI circuits.

Memory freq set to "unlinked" -- supposedly it's still running at 800MHz, but perhaps not. (Corsair XMS2, factory 5-5-5-18, 4x2048 DDR2)

Can anyone recommend where I should look, when increasing speeds are affecting video mode settings? Memory? Northbridge? HT?

Thanks in advance.

increase FSB doesnt effect that, something else must be going on. unless the NV chipset isnt locking the PCIE buss like it should be. FYI PCI doesnt run at 100mhz it runs at 33mhz, which is why i think your refering to the PCIE buss. incase you have a PCI buss selection and you bumped it to 100mhz. yea that would cause alot of problems but here im back to i dont think you have a pci buss lock option in bios. that option got dropped some time ago since they buss because auto locked at 33.33mhz.

running ram unlinked is not always going to get DDR2-800 it can be a little over or under. even in some cases will be the right speed, been there done that with a NV donated board(680i-EVGA).