Thanks alot Big Sam but i have a little problem and need some help of you

I have a system below

Asus P5WD2
Intel Pentium D 3.0Ghz
2x 6600GT @ SLI (after installed Big Sam's driver)
1GB RAM

My PSU is 530W, when i play games like 15 mins, my pc automatically restart, only when SLI is enabled, game does apprear nicer, better, but i got pc restart as well in less than 20 mins

Is my PSU 530W enough for both Pentium Dual Core & SLI running at a time ?

Please help thanks