Dead PSU?

[Wrenchy03]

I built a pc for my buddy yesterday and it started out working just fine until I went to update bios. When attempting to enter flash mode on his Msi gaming edge z590 the pc shut down and wouldn’t boot back up. I unhooked my psu from my pc and used it in his which worked to update bios and get back into windows. We then take the psu back to exchange it for another one and the new one does the same thing. When I hooked it to my pc his power supply will light up my motherboard but will not power on. 
his specs:

intel i7 10700k

msi gaming edge wifi z590

corsair vengeance 2x8GB

corsair cx750M psu

samsung 980 1TB

samsung 870 1TB

[Guest]

Ok.  Let me try to get this right.

 

• CX750M in friend's PC.  Worked initially.
• PC shut down in the middle of BIOS flash.  Would not power back on.
• Replaced PSU with one from your PC and PC works again.
• Exchanged PSU for another CX750M and it STILL does not power up friend's PC.
• Put friend's CX750M in your PC and it doesn't power up either.

If that's the case:

 

• Are ANY of the power cables being used on the CX750M cables that DID NOT come with the CX750M?
• Can you do a "paper clip" test on the CX750M to see if you can get it to power up without being hooked up to a PC (example: http://jongerow.com/PSU_test/index.html)?

 

[Wrenchy03]

22 minutes ago, jonnyGURU said:

Ok.  Let me try to get this right.

 

• CX750M in friend's PC.  Worked initially.
• PC shut down in the middle of BIOS flash.  Would not power back on.
• Replaced PSU with one from your PC and PC works again.
• Exchanged PSU for another CX750M and it STILL does not power up friend's PC.
• Put friend's CX750M in your PC and it doesn't power up either.

If that's the case:

 

• Are ANY of the power cables being used on the CX750M cables that DID NOT come with the CX750M?
• Can you do a "paper clip" test on the CX750M to see if you can get it to power up without being hooked up to a PC (example: http://jongerow.com/PSU_test/index.html)?

 

That is the case and I should’ve mentioned I tried using my jumper on it and got nothing on both of them. No cables were added to it initially and it wasn’t until the second psu that I added another cpu cable being that the board has two 8 pin cpu connectors and the psu only came with one but has the option for another one. I’m half asleep after staying up all night trying to diagnose it sorry for the bad typing

[Guest]

4 minutes ago, Wrenchy03 said:

That is the case and I should’ve mentioned I tried using my jumper on it and got nothing on both of them. No cables were added to it initially and it wasn’t until the second psu that I added another cpu cable being that the board has two 8 pin cpu connectors and the psu only came with one but has the option for another one. I’m half asleep after staying up all night trying to diagnose it sorry for the bad typing

Is that second EPS12V (CPU) cable a Corsair cable or something you got from somewhere else?

 

Disconnect the second CPU cable and try it again.

 

Only Corsair cables should be used on Corsair PSUs.  If the second EPS cable came from an EVGA, Seasonic, Antec, etc. it's going to prevent the PSU from operating. If that's what you did, you're lucky if you didn't fry something.

 

[Wrenchy03]

2 minutes ago, jonnyGURU said:

Is that second EPS12V (CPU) cable a Corsair cable or something you got from somewhere else?

 

Disconnect the second CPU cable and try it again.

 

Only Corsair cables should be used on Corsair PSUs.  If the second EPS cable came from an EVGA, Seasonic, Antec, etc. it's going to prevent the PSU from operating. If that's what you did, you're lucky if you didn't fry something.

 

It’s from a Corsair hx1200 kit. Back up cables from my psu. It’s been disconnected only recently added

[Guest]

2 minutes ago, Wrenchy03 said:

It’s from a Corsair hx1200 kit. Back up cables from my psu. It’s been disconnected only recently added

Ok.  If it's from an HX1200 it should work. 

 

Very strange.

 

[Wrenchy03]

After jumping it for the third time it spun to life