Power Supply--I think--Problem

[Ocean]

My brother drove a computer I just built for his graduation up to the family house (packed away in a box and jammed between two seats so it didn't fall over or anything) and it wouldn't start up when he pluged it in. Inside the case the motherboard power supply had come unconnected and I tried again after reconnecting that.
When I press the power button both the cpu fan and case fan start up and then stop, and then after a few seconds they do it again, and keep on trying to start up. The case fan is connected directly to the power supply and the cpu fan to the mobo, and since they both behave the same this makes me think the problem is with the power supply. Anyone have any ideas on what the problem could be? Is there anything that i should be trying to eliminate issues?

Specs:
PSU: 500w Antec Earthwatts
Mobo: GIGABYTE GA-P35-DS3L
CPU: Dual Core e8400
Graphics Card: EVGA 8800gts 512mb
Ram: CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)
HDD: Western Digital 640GB 7200rpm

[The Wise Monkey]

Hmm, have you double checked all of the connections? How about the 4-pin CPU connector?

[Ocean]

All the connectors (including the 4 pin) have been checked over and are good, and I am still getting the same results. My brother just told me he probably unplugged it while it was hibernating... So could that have blown the PSU? Tomorrow I am going to switch it out into my computer to make sure it is the PSU.