Help with power supply problems.

650W is more than enough. This could be an overload or short. Disconnect everything not required to POST (including your hard drive) and see if you can at least get that far. If so, then add one thing back at a time (with power OFF, of course), until the symptoms return; you will have found the defective component. If it won't even POST, then your mobo may have a short. You can try taking everything out of your case. If that works, re-mount everything in your case, taking care that the mobo is on standoffs, and that there are no extra standoffs screwed into the case where there is not a mounting hole. Finally, run a strip of tape along the back edge, where loose PCI slot covers may be hitting something.

Oh, and what CPU cooler do you have? 0.5 seconds is awfully quick, but your CPU could be overheating if the cooler has popped loose.

I had the same problem. Finally replaced the CMOS battery. The PSU was also done for, but those two replacements fixed the problem.

ok i still have the stock intel cooler :S, thanks for ur ideas ill try them out and get back to u asap with the results

no luck so far i have tried removing and re-attaching the stock cooler, replaced the CMOS battery and unplugged the power too my GFX card (which then beeped at me), hdd, optical drive; so that the only power cable that was left was the mobo and it still did the same thing. Any other suggstions :|

*Edit, the fans stay on for about 1second, and i read that if u remove the stock cooler the thermal pad is destroyed, i did not reaplly any thermal material, does this sound like it could be overheating?

You should clean off and re-apply new thermal compound.
Plug the power back into the graphics card, but no other perepherals.