Will my new (possibly) broken motherboard short out my new PSU?

Oct 16, 2018
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OK everyone, please be gentle.
I recently purchased a brand new MSI X470 Gaming Plus motherboard and a new AMD Ryzen 2700X CPU. I took my old motherboard out and installed the new one in my case. However, I was stupid in that I plugged the 6+2 VGA cable from my PSU into the 8 pin CPU power slot on my new motherboard. Upon turning it on, there were some high-pitched beeps, then an electrical flash. After that I tried turning it on again, and nothing. I reinstalled the old motherboard, and still nothing.

I came to the conclusion that I had fried my PSU (EVGA 750 B) when I used the EVGA PSU tester that comes with the unit, and nothing turned on. I ordered a new PSU and installed it with my old motherboard.

My question is this: If I installed the new PSU (EVGA 750 PQ) with the new (possibly broken) motherboard, and installed every wire correctly, is there still a chance I could fry my new PSU, or will the motherboard just not turn on.