Backgound: My old PC worked fine for a few years, then I noticed a burning smell, and the system shut off and wouldn't turn back on. The smell was coming from the psu so I replaced it with a corsair gs700, but it still wouldn't turn on, no post or boot, the only thing that was powered was the usb port (I could charge my cell phone on it). After searching the forum a bit, it seemed my mobo went bad, so I decided to buy a bunch of new components for a new build.
The new stuff arrived, and i put everything together with a lot of help from this forum, but i can't get the thing to turn on. When i press the power button, the led on the psu lights up and the fan spins, both for half a second, then they stop. The case speaker makes one short, faint beep, then nothing. I tried removing the ram, same result. I removed everything except the cpu and the cpu heatsink/fan, same result; psu led and fan spin for an instant, then stop. No post, no boot. Oh and the usb port on the front of the case is powered. I tried this again with the mobo "dangling", that is, not screwed in, not touching the case, same result.
Could this be a doa power supply? It lights up and spins for that half second, and it did pass the paper clip test. I don't have another psu to try, nor do i have a volt meter. Any advice would be appreciated.
Case: Thermaltake commander ms-i
CPU: core i5 3450
MOBO: ASRock H77 Pro4/MVP
GPU: Radeon Sapphire HD 7950
RAM: Corsair Vengeance 4Gx2 DDR3 1600
PSU: Corsair gs700 (same one i tried to use in my old pc before determining the mobo was bad.)
It could very well be the PSU. There is a small chance that whatever caused your previous PSU to fail could have been the result of a motherboard issue and that could have then caused the same issue with the new one. Highly unlikely, but there is the chance. I would start with returning the PSU and see where it gets you next. You have to start somewhere and it's the logical choice.