Let the numbers speaks for themself

Opteron 170 @ 3.0GHz Vs. FX57 @ 3.0GHz
300x10.0 , HTT x3.0 for both Opty and FX
Watercooling for CPU (Swiftech Storm + MCP655 + BIP II)
DFI LP UT nF4 SLI-DR Xpert
2x1Gb , 250MHz @ 3.0-4-3-7-1T
GeForce 7900GTX/7900GTX SLI - 650/1600
Win XP Pro SP2 , FW 84.21WHQL

3DMark's and Aquamark3 (ForceWare sett. : Highest performance ) :












The only games i found that benefit from from Dual Core (well ... may be Serious Sam 2 will too ) :

Driver settings : High Quality , V.Sync=Off , AFx16 - forced , AA - appl. controlled , optimizations - off , Gamma Correct antialiasing - on , Transparrency AA - ON > Supersampling .