PSU going into protection means you havea short on the board. Recapping will not solve the issue. You need special equipment and skill to release the short.

When does PSU enter protection mode, when you connect power, or when you switch the board on via power switch?

Its directly when I turn on the power on the PSU. (Before turning on the power of the system.)

Joakim wrote on 2024-02-17, 14:55:

Tried multiple PSUs and both go into power protection mode.

how do you know that?

Can hear the PSU click and won't give power for a while until it has 'rested'. But you are right, maybe I have assumed too much!

then
>I measured on the ATX connector into the motherboard and no rails are shorted.
is not correct. Without pushing power button the only rail active is 5v standby - purple cable pin 9, measure between pins 7 and 9 on mobo ATX connector

rasz_pl wrote on 2024-02-17, 16:08:

then
>I measured on the ATX connector into the motherboard and no rails are shorted.
is not correct. Without pushing power button the only rail active is 5v standby - purple cable pin 9, measure between pins 7 and 9 on mobo ATX connector

This is helpful! Thank you.

I got the tip to poke around and measure resistance on capacitors. I found two caps with the same values close to the ram slot that measured differently. Removed them from the board and one of them had failed closed. Maybe it is the reason, maybe it's nothing but I will try to replace these two and see if it works and if it does, do a full recap.