I cannot get my computer to stay on for more than a few seconds.
The last time it worked properly was over a month ago. There was no impetus for the first issue. I was in the middle of playing a game when the computer shut off. I turned it back on and after two days of running fine, I plugged in my analog headphones after which the computer immediately shut off and at that point was power cycling.
I replaced the power supply and the computer kept cycling. It does not even get to the point that it can post or issue beep codes. I then replaced the case, CPU and motherboard. It is still doing the cycling and nothing seems to fix it.
I have gone through the checklist on this site. This is far from my first build. Before I replaced the case, I jumped the PSU and it worked.
These are the specs:
CPU -- Intel i7 3.2 quad core (new)
Motherboard -- G1 Assassin 1366 (new)
RAM -- Mushkin 998679, timing - 78720, 1.65v - 3x 2GB sticks (old)
CPU cooler -- stock, Intel (new)
Video Card -- VisionTek RadeonHD 5870 1G (old)
Power Supply -- Seasonic 150w X Series Gold (new)
Hard Drives -- Seagate 250GB SATA2, Seagate 160GB SATA2, Western Digital Caviar Black 1TB SATA2, Seagate 1TB SATA2 (all old)
DVD Drive -- LG SuperMulti DVD Rewriter, model GH20N515 (old)
Case -- CoolerMaster HAF 932 (new)
G1 Motherboard front panel accessory
Operating System - Windows 7 64 bit
That's really strange. Is there anyway that you can try a completely different power source? Maybe a wall outlet that's on a different circuit and don't use any power strip. (I know you checked the PSU). The only other thing I can say is maybe whatever part was bad before, got replaced with yet another DOA part. Unlikely, but still a definite possibility.