Asus Maximus VIII Hero randomly doesnt boot

[Stryxus]

So iv been testing my motherboard for 2 days and iv finally decided to send it back for RMA. But then i had a thought, id come here to ask if anyone here can figure this one out.

Randomly my PC wouldnt switch on in the morning, i took it apart and only left the motherboard with the cooler and cpu attached as well as 1 stick of RAM. I turned off my PSU then held the CMOS reset button for 3 seconds and it unpowered the motherboard, i then turned the PSU back on with the CPU 8pin and 24pin attached, i then pressed the start button on my mobo but the mobo only powered up my cooler and PSU for a split second and after this it wouldnt power up at all until i reset CMOS and turned my PSU off and on again.

I waited until today to get a new PSU which sadly has the same results as the old PSU.

My mobo does power up with just the 24pin but as soon as the 8pin is attached, it refuses anything.

I have NO idea how to fix this...

 

[Glanza]

Was this running everything at stock speeds and timings or did you have an overclock on previously?

 

[Stryxus]

Was this running everything at stock speeds and timings or did you have an overclock on previously?

Only the XML profile enabled for my RAM to use its full speed (3000Mhz) and EPU enabled. I seriously doubt Asus's own settings configurations would have done anything to it (excluding the ones which you can manually set and i dont dare to touch)