PSU/Motherboard Might be Shot...really need some help.

[shingouki]

So my pc was working just fine, then one day it suddenly shuts off with some smoke popping out from the PSU. So I bought a new PSU, and tested it. My PC now wouldn't power. No Lights or Fans or anything. Then after I tested various setups, eventually I figured out the new PSU would work fine and fully power up until I plugged in the cpu. So the mobo works, and all the fans work, but it wont power on as long as I plug the PSU into the CPU 4+4 pin slot.

I'm totally stumped about what's going on here, so I just need some direction about what to do from here.

My PSU is the EVO 750 G2: http://www.newegg.com/Product/Product.aspx?Item=N82E16817438017

My CPU is the AMD FX 8320: http://www.newegg.com/Product/Product.aspx?Item=N82E16819113285

and my Motherboard is the GIGABYTE GA-990FXA-UD3: http://www.newegg.com/Product/Product.aspx?Item=N82E16813128514

Please, can someone help? Thanks in advance!

 

[George Phillips]

Do you mean the motherboard will work if the 8-pin CPU power connector is NOT connected with the corresponding connector from the new PSU?

 

[shingouki]

Do you mean the motherboard will work if the 8-pin CPU power connector is NOT connected with the corresponding connector from the new PSU?

Yes, that is exactly right.

When I plug everything in BESIDES the CPU power connector, the case power button works/lights, and all the fans turn on, including the cpu fan, which leads me to believe the motherboard is working.

 

[Dragos Manea]

It may be the VRM for the cpu on the motherboard or it can be the cpu u cant tell for sure but i tend to think that is the VRM (the motehrboard) which are powered by the 4+4 PIN connector.

 

[George Phillips]

That 4+4 power connector supplies power to the components on the motherboard to supply power the the CPU. If the entire system fails to start when this power connector is connected with the connector from PSU, the particular part of the motherboard is likely fried.

It's very crucial to pick a quality PSU for the system because when a rouge PSU goes bad, it usually takes down many other components with it. I'd advise to check drives and back up everything. Then upgrade or move on to a new system with new components.