poor hd4870x2 performance

[lee2008]

My system spec:

Windows Ultimate 64bit (SP1)
Asus Rampage Formula motherboard
Gigbyte HD4870x2
Q6600 @3.0Ghz
3Gb Ram (standard 667Mhz)
Zalman PSU 750w
Raidmax Sirius system case

On Crysis, using the optimal settings the graphic settings are set to high, but using my old 8800GT the settings were set to Very High.

Can someone tell me why with a card about 20 times better than a 8800GT why is the performance not as good. Even on Settlers: Rise of a empire with the settings maxed and res at 1680x1050 fsp are no more than 30-35, and Bioshock is about 35-40 fps. On crysis i am getting about 5 extra fps.

I've even changed from Vista Home Premium 32bit to Vista Ultimate 64bit hoping that would change but still no luck (when i installed Ultimate on my C drive i have 2 copies of windows files, one says 'old') might this be causing it, or could it be my motherboard, because i've already changed the card 3 times and also changed the make thinking it was a faulty HD4870x2

 

[Nik_I]

the only thing i can think of that could be causing that is that you might not have enough power for your system. i know you have a 750W psu, but maybe it's not delivering all of that. and i'm not sure how good zalman psu's are. for cooling they're good, but psu's are different.