Newly built PC starts for a split second then shuts off

ndrais

Commendable
Nov 13, 2017
18
0
1,510
Hello everyone

My friend and I built a new PC today with the following parts:

msi Z370 A-Pro
i5-7600
Pure Rock BeQuiet Fan
msi GTX 980 Ti
2x8GB Corsair Vengeance ddr4
Corsair RM650x PSU
Samsung 850 Evo 500GB
WD Red 2TB

Now since this is not my first time building a PC I am 100% sure we assembled everything correctly (and we made sure all cables are plugged in the right way).

Now the problem is, when we try to turn the PC on, the fans start spinnig, some LED's blink and it immediately shuts off again. This only occurs when the 8pin CPU cable is connected to the PSU, if we remove it, the PC starts.
We thought it might be some error with a driver so tried to install that, but we didnt get a signal on the screen either (hdmi plugged into mobo directly or GPU didnt make a difference).

So my assumption is, that we got delivered a faulty mobo (or cpu?) or we somehow get a short-circuit, although I doubt the latter. However, before returning it, I thought I'll ask you guys first.

Thank you so much for any advice!!