Question PC powering-on issue ?

Jul 24, 2021
So I've looked at about 100 threads about motherboards being the reason for no power or PSU and still not worked this one out.

Situation: so I've been having issues where my PC wouldn't turn on and eventually just stopped turning on. So I replaced the mother board, cpu, cpu cooler, ram and psu, with below

Ddr4 corsair vengence ram
i7 10th gen cpu
Z490-A pro msi motherboard
Corsair 750W gold+ psu
Coolermaster cpu fan

I initially set all this up in my PC inside a phantom nzxt case, with a geforce 970 gpu that i already had and samsung 860 evo ssd
Straight off this didnt start, i was confident I had all the correct cables in and checked multiple times to see. I later removed the GPU and borrowed a mates psu to test if it was a power issue this then turned on fine. Leading me to think PSU issue. However when I plugged the gpu back in no dice wouldnt start again.

Ive since then done a paperclip test on both my new psu and it runs fine, I've also totally removed all the parts and set it up outside of the case.

Once out of the case I have managed to get it to power on once through joining the power pins, this was directly after resetting the CMOS. However in the exact same circumstances ive tried this about 50 times in slightly different ways to no success.

Effectively my question is have i been sent a dead motherboard, does this happen? or am I missing something as it seems highly questionable that all my new parts are having the same issue as my old parts.

Tried removing cmos multiple times (powered on after once)
Removed mobo onto an insulated surface and booted once out of at least 50 times.
Tried paper clip test, psu fan spins.
Re-seated ram, a few times now.
24 pin and 8 pin power connected.

Still not consistently powering on.

Please help I'm so stuck 😂