I built 6 of these systems, all exactly the same parts, all worked with the exception of 1 which ran for a week then it restarted on it's own and now when I turn it on all the fans spin for 1 second then it does nothing.
I have a system speaker installed and no beeps occur, it doesn't stay on long enough to POST or give me any signs in which to begin troubleshooting. The MB Power light comes on when it's plugged in and stays on after the fans spin for 1 second then never boots, the HD doesn't spin, nothing.
It was working for 1 week running windows 7.
Here's the specs and what I've done to troubleshoot so far:
• ASUS Sabertooth X79 LGA 2011 Intel X79 SATA 6Gb/s USB 3.0 ATX Intel
• intel Core i7-3960X Extreme Edition Sandy Bridge-E 3.3GHz
• COOLER MASTER Hyper 212 EVO
• CORSAIR 500R Case
• 1 TB Seagate SATA Drive
• DVD Drive
• Geforce GTX 670
• Corsair 650 PSU
• Kingston DDR3 RAM 32GB
First I unplugged everything with the exception of the CPU & Cooler, and got the same results. I gradually added 1 component at a time and got the same results each time.
Then I replaced the PSU, same results.
Then I replaced the Motherboard, same results.
Then I took everything out and rebuilt it in a NEW CASE, same results.
The three things it could be are the PSU, the mobo, or the CPU. Since you have already switched the PSU and the mobo all that's left is the CPU. I would return it if it's still under warranty and get a replacement.
Finally solved my mystery...
Turns out the brand new out of the box power supply (the 2nd one as I replaced the first brand new one) was no good.
Started a new build, had no issues, swapped out the PSU with the build I was having issues with, and BOOM started up no problem.
Just to be certain put the PSU into the newer build and it wouldn't start.
So lesson learned, if you replace a PSU with a new one, that one might not be good just because it's new