Newly built computer won't power on, tried everything

[Matt_170]

A computer I've just built that SHOULD be turning on is not. Checked off all of the troubleshooting issues here: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

So, I'm running out of ideas here. We've gotten it to power on before, but I took the processor out, reapplied the paste (a minuscule amount got on the pins but probably not enough to cause an issue), and inserted a new graphics card.
The CPU fan turns on very briefly before the whole thing shuts down. The system speaker is silent, no beeps.

Specs:

CPU: AMD FX-8350
Motherboard: 970M Pro3
RAM: 2Gb, 4Gb, 4Gb sticks
CPU cooler: Stock AMD Wraith cooler
Video Card: GeForce 8400 PSI
Power Supply: EVGA 500W 80 PLUS
Hard drive: 1x 500 GB
Case: Old generic hp case

Like I've said, been through everything in the link below and I'm running out of ideas. Please help!

http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[alexoiu]

Try testing the board outside the case, only CPU and CPU fan installed, both 24 and 4/8 pin power cables connected. If still the same, it might be a short at the CPU level, or a board issue and I suggest RMA-ing both board and CPU.