Power failure PC won't boot

[xiownthisplacex]

The power went out the other day and my pc no longer boots up properly.
I don't hear any beeps (although I don't remember if it ever did or not before).
The fans spin (but they seem slower than usual).
No display.

I have done most of the usual:
-Reset bios
-Remove battery
-Unplug, hold power button for 1 min
-Removed RAM, tried with many combinations
-Unplugged everything except power supply (no hdd, usb etc plugged)
-Removed GPU

I also bought a new PSU, got the new one yesterday and still a no go.
Here is a description of the rig:

CPU: Intel Core i7-5820K
HDD: 1T SSD Samsung
MEMORY: 16GB (4GBx4) DDR4/2400MHz Corsair
MOTHERBOARD: MSI X99A
POWERSUPPLY: EVGA 800 Watts
VIDEO: NVIDIA GeForce GTX 970 4GB GDDR5

Anymore suggestions on what I should try?

Thanks in advance!

 

[atljsf]

if you already tried all that, mainboard change to discard mainboard as damaged is what i would try now

also try to wirk without gpu to discard gpu as the possible source of the problem

 

[xiownthisplacex]

Yes sorry, I have also tried without the GPU and didn't work.
I was hoping not to change the motherboard, I don't have a spare one around. Any other way to test it without swapping it for another?