My Pc simply stoped working. I cant start pc with power button,only where PSU switch. The motherboard powers up, but goes no further than that. I get no beep code,no green light on motherboard and no video, CPU Fan working,MB fan working, GPU fan working. Processor: AMD-athlon64 FX-57 Memory: 2GB Crucial Motherboard Asus A8N-sli deluxe Video Card: Asus Dual NVIDIA GeForce 7800GT Extreme 512MB ready SLI OLd PC What could be faulty?