I recently built a computer loaded windows 10 onto it and everything was fine. I installed a game on steam to benchmark and within 5 minutes the computer completely turned off. I tried to turn the computer back on and got nothing so i took it apart to see if i could notice anything wrong and i found nothing. I then put it back together and got a beep code(1 long 3 short) which indicates with my motherboard a video card error. So i figured the video card was dead had it TESTED in a friends computer it worked fine tried it in mine again and got nothing. I've also tested it in both PCI-E slots and both give no power at all to the GPU and the fans on the GPU dont spin at all but everything ELSE seems fine. I have no idea where to go from here, Is it a bad motherboard or bad PSU? Also note the GPU was initially my friends but he upgraded to a new one and gave me his old one. This being the same FRIEND who tested it for me when it stopped working.
PC specs :
CPU: FX 6350
CPU Cooler: Cooler Master Hyper 212 Evo
MOBO: Gigabyte GA970A-D3P ATX AM3+/AM3 Motherboard
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory
Storage; Kingston SSDNow V300 Series 120GB 2.5" Solid State Drive And Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive
Power Supply: EVGA 600B 600W 80+ Bronze Certified ATX Power Supply3 of 5 rating and lots of DOA's.... Id pull your CPU from it and get a board swap under warranty.

https://www.newegg.com/Product/Product.aspx?Item=N82E16813128627EGADS....3 DOA's...kinda rare for Gigabyte....

Also the vid card was never listed...even though it remains a suspect in this...Its too bad the motherboard doesnt have integrated GPU to fall back on for a lower level of troubleshooting. I have doubts its the power supply, and thinking its main board.

**Hopefully if its a video card that REQUIRES 12V Molex power, that the power is given to the videocard and not just relying on the PCI-E power. That is one way i could see a video card post beep occuring and not have it the power supply or motherboard.

What video card are you running... got us both CURIOUS now?