Unable to boot the 2nd PSU with add2psu

Hello,

I’ve been troubleshooting this issue for the last 2 days to no avail.

Setup:
Primary PSU - Superflower 1200W SE - powering the mobo + 2x 3090s and the risers they are on
Secondary PSU - ASUS THOR 850W / Corsair 760AX - powering 3060Ti and 5600XT and the risers they are on
Both PSUs are interlocked with an add2psu

Problem:
Primary PSU boot up no problem. 3090s are hashing away stable. But no matter what I do, the secondary PSU just won’t boot up.

Troubleshoots:
Swapped the secondary PSU for another - same issue
Checked both secondary PSUs on a dummy MOBO - can power on, no issue
Swapped add2psu - same issue
Isolated the 3060Ti and 5600XT - same issue
Checked power outlets - nothing wrong with them

I’m out of ideas. I’m beginning to suspect that the MOLEX isn’t closing the relay? But all MOLEX pins are standard no matter the PSU, isn’t it?

EDIT: Solution found. See 2nd post.

Son of a bish

As it turns out, I mistakenly used the 6P-to-MOLEX cable from a different PSU than the primary one. :expressionless:

Corrected it with the right molex cable this time, and voila… dual PSU is now functioning as intended.

I’ll leave this topic here in case someone else is facing the same issue.