I just built a new computer, and it worked perfectly for a few days. However, yesterday I left the computer on, then went to do something. When I came back, the computer was completely turned off. There weren't even any of the LED's inside the mobo, which usually stay turned on even when the PC has been shut down. NOTHING in the computer is turning on, no fans, LED's, nothing. So is there a way to isolate the problem? Is there a way to make sure my power supply is working properly? I checked to make sure all the power cables are fully plugged in,as it's been suggested that a connection could have come undone after a few days, but this does not seem to be the problem. Also, if there's a way to avoid taking out and replacing every single component one at a time, that's preferable. My power supply is the epower Lion, http://www.epowertec.com/power_lion.html I'm not so suspicious of this--I know it's a good psu. I have an Abit KN8 mobo, an evga 7900GT, AMD 3800x2, 2 gigs of corsair value select, a seagate baracuda 250GB HD, an NEC DVD/CD RW drive, and the CPU is cooled by a titan vanessa l-type. My generic case (http://www.geeks.com/details.asp?invtid=BLU-CP702-3&cat=CAS) came with a 450W PSU which I did not use.