T7400 PSU won't start if ATX 24 pin is connected

Gigadroid

Commendable
Apr 11, 2016
4
0
1,510
Hey guys,
I recently bought a used Dell T7400 PSU.
Now I wanted to replace the other PSU, but I have some issues.
The T7400 PSU has a button which, aslong as it's pressed, turns it on.
This works fine, till I actually connect cables to it.
Then neither the button nor the actual power button of my PC seem to do anything.
I nailed it down to the ATX 24 pin connection being the reason, because if it's not plugged in, I can start the PSU.
Is the T7400 incompatible with an normal mATX board?
I'm trying to use it with an B85m Pro 3.
The setup is currently working with a usual PSU.

Thanks in advance!
 
Can you give me a link to this exact power supply, or post an image of this "button" you're talking about? I highly doubt you're trying to attach cables to the power supply, do you mean attaching cables to the motherboard and rest of the computer?

I wouldn't be surprised if the pin-out of the main 24-pin ATX cable is proprietary and different than normal. But I'll need a link, or a picture of the main ATX cable.