Sudden Pc restarts

[Lancertanvir]

So 10-12 days ago I posted regarding this matter, What happened was pc restarted everytime I played games on it.

I thought it was a heating issue but it wasn't as some of the learned people of the community has pointed out and I am thankful to them.

 

BUT!!!! then something else happened.. I disconnected the cpu, motherboard, gpu and hdd power cables and while the mobo was inside

my case, and I connected an external PSU so that I can test whether it was actually my psu that had went bad.

 

BUT PC DIDN'T EVEN TURN ON... but i connected my old psu again and it started working. Something that I couln't explain

with logic. Or may be the logic is something I am not capable to understand.

 

**checked 3-4 times, the connections are alright.

 

I'd like some help in this matte. Still don't know what's going on with the pc. Thanks in advance.

 

My PC:

processor: Intel i3 6100

Ram: corsair vengeance 8GB ddr4 2400mhz

GPU: sapphire r7 360

PSU: corsair VS550 

CPU cooler: Cooler Master TX3 evo