Rig will not start when I push the power button

[SOCOM_HERO]

I've had a PC for some time now (https://pcpartpicker.com/list/crXbDj) and sporadically it will not turn on, which is becoming slowly more and more common when I hit the power button on the case, or even on the motherboard itself. The LED strips will light up, and the RGB memory closest to the CPU socket will also light up, but the power to the system does not start. If I hold the power button down for about 5-10 seconds, the lights will go out and then if I hit power again, the same thing happens. If I turn off the PSU, once the caps drain, all lights go out, and I can repeat the process over and over to no avail.

 

Then randomly, it will power on when I hit the button.

 

I've tried pulling the CMOS battery and replacing it. I've tried unplugging the 24 pin and plugging it back in, reseating ram and swapping power cables to new outlets. None of those steps changed anything.

Is my PSU going bad? Motherboard?

 

If I have to upgrade, I'd basically build a new system at this point and try to diagnose this one later as a hand-me-down or sell it for parts. I'd need a new PSU, mobo, RAM, CPU, case and cooler as my bespoke watercooling days are behind me with this one. Basically my drives and GPU would stay.