Upgraded PSU and computer won't post, if old PSU is plugged in pc boots

0530cg

Prominent
Jun 14, 2017
2
0
510
I'm having a huge problem getting my pc to boot after upgrading PSU's due to the old one causing my gpu to cut power under load and I would get a flashing screen.

So I bought a new PSU, originally I got a refurb corsair cx850m. I wired everything up and in addition replaced all fans in my computer. When I went to boot it the back case fan spun for like half a second and then died. I repeated this over and over and I couldnt get anything to work. I rewired everything, no change. I even tried to reset cmos by sticking a coin inbetween the pins to reset it and that didnt work. So I figured it must have been the psu because it was refurbished so I went back to the store and got another, same issue. No biggie it must just be this psu, back to the store and I got a cx750m refurb. Same problem no post. I plug in my old psu and it boots straight to windows. So I figure it must be the new psu, back to the store. I just bought a new corsair cx650m opened it up and it wont post. The back fan rotates for half a second and then nothing.

I'm starting to think it might be a motherboard issue, I really don't want to buy a new motherboard and have this issue because money is tight.

My component list is:
intel core i5 2500k
ASRock Z77 Pro4
AMD Radeon RX480
2x4gb corsair ddr3 ram, not sure what the specs are but they work with old psu
Samsung 850 evo 500gb SSD
WD blue 1tb
4x corsair AF120 performance edition fans

My old psu that works is a PCPower & Cooling Silencer MkIII 600w
The new psu that I bought is a corsair cx650m.

If anybody has any help to offer it would be greatly appreciated because I have become very frustrated after 4 trips to microcenter and countless hours of troubleshooting.
 

0530cg

Prominent
Jun 14, 2017
2
0
510
The 8 pin CPU connector would snap in, I checked every wire at least 3 times per power supply.

Currently I have my pc running on my original power supply, but have the same screen flashing issues.