Team Fortress low FPS with new Hardware 8800GT

Hey Guys, I need help!

So, I recently built a new PC and in TF2 it seems like I am getting extremely low FPS no matter what the graphic settings.

Machine is: AMD X2 5600+ (dual 2.8) GigaByte M61P-S3, 2GB Gskill DDR2-800 (5-5-5-15), OCZ 700W PS, Dual WD SATA2 7200RPM Drives in RAID 0, Running XP SP2, Direct X 9c Through GeForce 8800GT 512 to a LG 22"WS @ 1680x1050.

In TF2 I get 100+ FPS at Spawn and in intense action it can drop to ~25 FPS. This seems unusual.
I have updated all drivers including Chipset, Video (New, Old, & Beta) Tried disabling everything in msconfig, updated BIOS FW, tried various BIOS configs, unplugged peripherals and anything else I can think of. Even if I run the monitor @ 1280x1024 it does the same thing.

Any Suggestions???

3dmark kicks out a 10k. I had a 1950Pro and It was 5K and the performance was about the same.

heat issues? Check those temps. Maybe also try some different/beta drivers for the card.

with a 2900 pro that game, with 16x AA at 1280x1024 at all times on max settings, never gets slow enough for me to notice.
(btw, its a great game )
does it vary if you change the gfx settings down to bottom?

hello smoked turkey and all,

and you done it (rebuild) ?

what did it give ?

because I have the same problem.

I have a DualCore 6300 @2,4Ghz ; 2Go RAM ; 8800GT 521Mo

Crysis OK (in High) , Far Cry OK, but TF2....

between 10 and 50 with all high, AA2x (but 4x or 8x is the same), bilinear
i changed once to noAA, I raised to 80fps, but 5 minutes later : again, 25fps....

mostly, I seem to remember that "at beginning" (that I had the game ) it was always fluid
so I think also , all reinstalling might be the way.... the long way :-(