This thread on insanelymac should offer you a solution for the cpus=1 to get all cores working - it seems there's issues with the nForce 570i, 590i, 610i, 630i, 650i, and 680i mobos. There's a pdf containing the correct bios options plus you may need to install an older AppleACPIPlatform.kext.

In regards to your graphics card, you should look into using an EFI gfx string, you can use a program called EFI studio which has many premade strings for most cards.

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 Mac OS X 10.6.4 Retail || Intel Core2 Duo E8200 2.66GHz || Gigabyte G31M-ES2L || GeForce 6600 GT 128MB || Realtek ALC883 Audio || Realtek RTL8169 LAN || Samsung SpinPoint F1 1TB HD || Sony Dual Layer IDE DVD RW DW-D22A || Apple Aluminium Keyboard || Mighty Mouse

 MacBook Pro || 2.4Ghz Core 2 Duo || 200Gb HD || 2Gb Ram || NVIDIA GeForce 8600M GT

 iPhone 4 || 16Gb