3870 X2 scales much better than 8800 Ultra with more CPU power
 

after our initial review, we tested what's happening when you offer the HD 3870 X2 and the Geforce 8800 Ultra more CPU power. We compared several games like Crysis, Call of Duty 4, Need for Speed: Pro Street, Bioshock and UT3 with two CPUs (Core 2 Duo E6750 standard versus Core 2 Quad QX9650 @ 3.6 GHz) and found out that the 3870 X2 gains 32,5 percent with the new processor whereas the 8800 Ultra gains just 13,2 percent. And we used very demanding settings like 1920x1200.

http://www.pcgameshardware.de/?menu=...=769646&page=1

Very interesting

their results have the 3870 X2 surpassing the 8800 Ultra with the CPU OC'ed

Now is it the OCed CPU or the extra cores that make the difference?

I would suspect it is the higher CPU frequency. And I suspect that because I think the gains are from the higher-clocked CPU is better able to handle the extra driver overhead caused by Crossfire, which leaves more CPU time for the games. That would be my theory, at least...

only explanation possible:)