New system build issues with PSU/MB

leonnewkids

Prominent
Dec 2, 2017
3
0
510
Hi fellow tech guys,

I just build a new system without CPU yet, and i tried to see if it would start already.
But my motherboard doesnt light up nor does my PSU start.

As soon as i test the PSU, it starts working and all lights go green.
If i then connect the cable again to the motherboard, it lights up for +- 5 seconds. Probably the power that is still stored from powering on with the supply tester.

Does anyone have a clue what might cause this, and how to resolve?

Thanks so much!