ATX 3.0 Power Supply issues EATX motherboard

[nicholsaq]

First off i want to say this: Yes, I am stupid. What i am doing is dumb, but sometimes dumb is fun. I bought a A750 for $150 on black friday and i am trying to put it into my existing gaming rig. (pc part picker below) I want to run my secondary monitors off this card and just game on my rtx 2080. This is a dumb experiment i know. 

Ok now for the problem: so I had a nice EVGA SuperNOVA 650 P2  power supply but it would not have the power to drive both cards. I went to microcenter and picked up a 850W Seasonic power supply (listed in PC part picker below). This is a ATX 3.0 power supply though so I had to change basically all of my cables. I got the swap all done with everything plugged in correctly.....no post. no lights NADA. eventually i realized that the pinout on my 24 pin is different on the power supply side. (I had swapped it for the new one anyways) Everything I am reading online says that this should be the same. I was able to plug the old cables into the old power supply and confirm that the components are not dead. What gives? Is the new 24 pin different? 

 

PC sepcs: https://pcpartpicker.com/list/Ct6WBL

[emosun]

16 minutes ago, nicholsaq said:

eventually i realized that the pinout on my 24 pin is different on the power supply side.

if you used your old cables and plugged them into the new power supply and that power supply wasn't pinned correctly then you might have fried something.

return the machine to the original configuration you had prior to see if it's still functional.

16 minutes ago, nicholsaq said:

) I want to run my secondary monitors off this card and just game on my rtx 2080. This is a dumb experiment i know. 

well spoiler alert for your experiement , a secondary 2d monitor doesn't require much of any significant gpu power to run. meaning your 2080 was already capable of running it without any performance differences.

infact most gpus made within the last decade regardless of age or price point are capable of displaying a second 2d monitor without issues

[Ralf]

I asked my friend Duckduckgo and he said the pinouts are totally different on the PSU side.

 

https://pc-mods.com/blogs/psu-pinout-repository/evga-psu-supernova-cables-pinout

https://pc-mods.com/blogs/psu-pinout-repository/seasonic-focus-sgx-cables-pinout

[nicholsaq]

1 hour ago, Ralf said:

I asked my friend Duckduckgo and he said the pinouts are totally different on the PSU side.

 

https://pc-mods.com/blogs/psu-pinout-repository/evga-psu-supernova-cables-pinout

https://pc-mods.com/blogs/psu-pinout-repository/seasonic-focus-sgx-cables-pinout

Nailed it.