System cant boot to windows or get into BIOS

So everything is brand new I am getting ready building a 13GPU rig but I wanted just to test the system with 1 GPU and install windows etc before I install all the GPUs.

CPU i5 6500T
PSU Corsair HX1200i (1200Watt)
RAM Corsair Vengeance LPX 16GB 3000Mghz (2*8GB)
GPU RX vega 64.

So what I did is this, install everything (8pin CPU, 24Pin ATX and the 2 molex on the board)

I installed the GPU directly (like in a normal PC) on the x16 slot (the long one)

I installed power to the GPU directly from the PSU (like a normal PC using the 8pin connectors) .

==================

What happened

I inserted the USB with the windows installation and it automatically booted from it and tried to install, I selected my SATA SSD (512GB ADATA) it formated it and installed the files...

All went smooth to this point but at the point where windows installation says "restarting your PC in 10 seconds"

It restarted immediately and rebooted on a black screen (also my PSU fans although silent during the installation run very loud after booting into a black screen, but the fans on the GPU are not spinning -as they shouldnt since it hasnt load, the LEDS on the GPU are light) also keyboard lights and mouse dont work but lan led is light



trying to push the power button for several seconds or the reset button doesn nothing.

Only way to restart is to hard switch the PSU off.

Then on powering on the system again if I do it fast I get again loud PSU fan and black screen ...

If I hard power off the PSU (from the on off switch on its back) and wait for a little or click on the mobo poweron button (while PSU is OFF) and then I power on the PSU and push the mobo poweron button THEN I see the mobo splashscreen with the asrock logo (and the fans on GPU spin normaly).


But as soon as I see the windows logo loading the system restarts to black screen with the PSU making loud fan noises,GPU fans dont move

If I do the "ritual" described above (to avoid black screen and see the asrock logo)

and try to push del to get into the bios (so before getting to windows loading logo) the system restarts again with the same symptoms(black screen etc).

So I cant get even into the bios!

What I tried: reseating ram.
Rseating GPU
Trying only one RAM stick (and tested both while doing that doing various attempts)

Trying the single stick from a different slot

Disconnecting the 2 molex connectors onboard

Nothing works.

I doubt its any peripherial because everything is brand new but mostly because I cant get into the bios... I doubt it is the CPU because at least on my first boot windows setup loaded normally.

Is the board DoA£