I have two geforce 8600GT in SLI, Pentium 2.44 Core 2 Duo, 2 gig ram 3 case fans tow hard drives and two DVD drives. My other power supply broke i needed my computer quick so a store put in a 520w power supply ever since then when i unplug my computer and replug (move it or something) it in when i start it up it starts then turns off i have to push the power button repeatedly times for it to work the store also ran out of power plugs for stuff so they spliced the fan into another plug ever since then the fan goes on and of ever two seconds. is it because i need new power supply and how big would you go?