Mining / Power

Run Two Power Supplies in One Rig, Properly

Past a certain GPU count one supply cannot do it. Two 750 watt units are also often cheaper than a single 1500. The same wiring applies to any dual supply build, gaming or storage or a home server.

The one part you need

You need a 24-pin power splitter.

It plugs into the motherboard where your main supply used to, and takes a 24-pin connector from each supply.

The branch for the second supply only has two wires in it.

Those two wires are the whole trick. They carry the power on signal from the motherboard to the second supply, so the board is what decides when it turns on.

Wire it up

Unplug the 24-pin connector from the motherboard.

Plug the splitter into the motherboard in its place.

Plug both supplies into the splitter.

Put the supply that also feeds the motherboard CPU power onto the full 24-wire side.

Put the second supply onto the two-wire side.

Hang your extra GPUs off the second supply.

Test boot it.

If you run the rig without a power button, set the board to power on automatically when it senses power. That setting lives in the BIOS, usually under a restore on AC power loss option.

Do not use the paperclip trick on a rig you leave running. Jumping the second supply on by shorting its own pins works, and that is the problem. It is now on all the time and knows nothing about the motherboard. Shut the machine down and you still have graphics cards powered up in a box that thinks it is off. That causes exactly the kind of intermittent, hard to trace faults you do not want in a rig running unattended. Tie the second supply to the board's signal instead.