I just finished building this PC a few days ago, here's the specs:
CPU - AMD FX-6350 3.9GHz 6-Core Processor
Motherboard - Gigabyte GA-970A-UD3P ATX AM3+ Motherboard
RAM - Crucial Ballistix Sport 8GB (1 x 8GB) DDR3-1600 Memory
Video Card - XFX Radeon R9 380 4GB Double Dissipation Video Card
PSU - XFX 750W 80+ Bronze Certified ATX Power Supply
Yesterday everything was working perfectly, I was transferring files from an external hard drive plugged into a USB port on the front panel. Last night when I went to sleep I shut it down, and unplugged the external drive since it's got an LED and I have some trouble sleeping with those in the room. Today, booted it up and again everything was working fine for several hours, until I went to plug the external drive back in - immediately when attempting to plug in the USB, the computer shut itself off. Surprised me since it was the same USB port and was working fine last night. But after unplugging it and trying to boot up the computer again, from the sound of it it seems to be turning on fine, fans and hard drive and everything, but there doesn't seem to be power going to the mouse or keyboard and the monitor is getting no signal.
So far I have tried opening up the case to take a look and unplugging/plugging everything back in - nothing appears to be damaged as far as I can tell, but still not working. The one thing I'm not sure about is POST, I'm not hearing any beeps but I didn't hear any when it was working, and I am thinking that's because there didn't appear to be a front panel speaker on the case I have, so nothing plugged into that header on the motherboard. Again, not sure though.
EDIT - seemed like it might have been a short from the front panel USB, so I tried unplugging that, but still the same problem. I just built this so everything's under warranty, I'm just not sure how to verify where exactly the problem is. Motherboard?
Edited by vvarhound, 07 February 2016 - 08:32 PM.