Question Computer won't turn on if I have the cpu power plugged in

[-Pickle]

Hello, so on Saturday I was using my computer just playing some valorant when it suddenly turned off. I just thought maybe I had nudged the power cable or something so I tried turning it back on and nothing happened and basically thought I'd narrowed it down to a power supply problem, so I ordered a new power supply that came today. Connected everything and nothing happened. I figured out that it would start up if I unplugged the cpu power plug. I have tried different graphics card different cpu but nothing. I looked at the capacitors on my MB and they all look fine.

Any help would be greatly appreciated.

Thanks

 

[rgd1101]

and it turn on without cpu power?
full system spec? include make and model of the psu

 

[-Pickle]

Yeah, it turns on without the cpu power plug in.

Ryzen 7 2700x
GTX 1050ti
8gb corsair 3000mhz
The psu is just a generic 500w one from amazon (im pretty sure theyre all the same)

 

[rgd1101]

Yeah, it turns on without the cpu power plug in.

so it working?

 

[-Pickle]

No, because if I plug in the 8pin cpu header then it doesnt boot

 

[rgd1101]

No, because if I plug in the 8pin cpu header then it doesnt boot

but you said it turn on.

 

[-Pickle]

Yeah, it only turns on if that is unplugged

 

[-Pickle]

And you need that plugged in to get power to the cpu i believe

 

[rgd1101]

I wouldn't call the turn on if it doesn't work.

test with another known working psu?

 

[-Pickle]

I have, same thing happens. Sorry, by that i meant the fans spin up and the lights turn on

 

[rgd1101]

test with another gpu?

 

[Karadjgne]

No, because if I plug in the 8pin cpu header then it doesnt boot

There isn't an 8pin cpu, there's only a 4+4. Make sure you have the right connectors.

 

[onespeedbiker]

What the OP likely means is when the CPU fan is plugged into the CPU fan port it will not boot; usually the opposite is the problem. If this is the case, I would check the pins in the port and the fan plug. If they look good, you might want to look for a new heatsink/fan and see if it fixes the problem.

 

[-Pickle]

There isn't an 8pin cpu, there's only a 4+4. Make sure you have the right connectors.

Sorry by that I meant if nothing is plugged into it

 

[-Pickle]

What the OP likely means is when the CPU fan is plugged into the CPU fan port it will not boot; usually the opposite is the problem. If this is the case, I would check the pins in the port and the fan plug. If they look good, you might want to look for a new heatsink/fan and see if it fixes the problem.

I'm not talking about the cpu fan port, I mean the 4+4pin

 

[Karadjgne]

Well normally a motherboard/cpu will require both the EPS and the Mains plugged in for function, but there's a few reasons why it fails if the EPS IS plugged in. Can be bent cpu pins, defective mobo, miswired psu, miswired EPS, motherboard short to case etc.

 

[-Pickle]

I have tried with another cpu and had the same thing

 

[-Pickle]

I have 'breadboarded' it and tried a different graphics card, cpu and psu and the same thing happens each time. Which leads me to believe that it may be the motherboard? I have had a good look at it and cant see any bad capacitors the motherboard is the a320 sh2 (i dont think i mentioned it before)

 

[-Pickle]

A320M-S2H**

 

[coastie65]

Okay, you said that it starts up when nothing is plugged into the CPU headers. Okay. As stated, those are 4+4 ( total of 8 pins. The is a Connector from the PSU that is 4+4 and CPU specific. There is an 8 pin Connector as well and you should NOT be using that. What they provide as far as current goes is different.

 

[-Pickle]

I RMA'd the motherboard (I got a replacement from Gigabyte) and all is good now