[SOLVED] Old power supply with 4-pin CPU connector powers just fine, new one with 8-pin CPU connector gives red CPU light and no POST.

[Tamramsy]

The old power supply was pulled from an old office PC, the new one is a thermaltake toughpower gf1 650w. Whenever I power on the PC with the new PSU (8-pin ATX CPU connector) it won't POST and gives me a red light on the motherboard indicating a problem with the CPU. The old PSU (4-pin ATX CPU connector) works just fine but won't have enough wattage for the upgrade I'm trying to do.
Specs:
Intel core i7-9700k
Gigabyte Z390 UD
Thermaltake Toughpower gf1 650w
Nothing else is plugged in right now, but if you need the other specs I can share.

 

[COLGeek]

Make sure that both the 8-pin and 24-pin PSU cables are firmly attached at both ends (motherboard and PSU).

Also, make sure you don't re-use any power cables from your old PSU with your new PSU. Cables are not interchangeable between makes/models.

 

[geofelt]

Verify that you are using the 4+4 cpu EPS cables and not pcie 8 pin cables.

 

[--SID--]

Reset CMOS

 

[Tamramsy]

Solved. It was user error. Not sure how to mark this as solved.

 

[Vic 40]

Solved. It was user error. Not sure how to mark this as solved.

What did you do?

You can btw click on a trophy icon beside the answers given, not your own though, pick one that was most helpfull.

 

[Tamramsy]

What did you do?

You can btw click on a trophy icon beside the answers given, not your own though, pick one that was most helpfull.

I forgot to plug in the second connector for the 24-pin ATX cable to the power supply. Never used modular before.

 

[Vic 40]

That's fine , can happen don't worry about it.

Just wanted to know for those that might read this thread so they learn from it. 😉