Is this PSU or Mobo issue?

[xtroria]

I'd like to ask for everyone's opinion regarding this.

 

My friend's pc has been having problem where it gets stuck into a bootloop, not posting into BIOS after 5 seconds. Initially, I suspect faulty RAM or motherboard slots. Even with single ram stick on all 4 slots, it didn't boot up. USB doesn't work at this point and not providing power.

 

He took his pc to the store, didn't do anything to it, plugged it back home and viola, it booted up into windows, everything works like normal.

 

The next day he tried to turn it on again, bootloop again, he had DRAM fault indicator turned on.

 

After shorting clear cmos, still bootloop, GPU fault indicator turned on

 

Plugged out the power for 5 minutes, the motherboard leds turned on WITHOUT the pc being turned on. Told him to switch the PSU off and turned it back on, pressed power button and somehow, it booted into windows again, no problem.

 

So this sounded like generally a power delivery issue, caused by either motherboard or PSU.

 

He already has a thermaltake 80+ gold and whilst not TOTL, it's a decent PSU that shouldn't make his parts go ka-put.

 

His motherboard is Z390 Aorus Pro Wifi, already what you can consider a high-end motherboard