Question New build PC won't turn on unless I unplug and drain capacitors first

[Kazbeh]

Hi everyone,

I'm in the process of troubleshooting and trying to fix a persistent problem. I built a new PC this week, here are the specs (all new components)

ASUS RoG Strix B550-F (wifi)
Ryzen 7 5800x (watercooled with Lian Li Galahad 360)
Samsung M2 SSD 980
ASUS TUF GeForce RTX 3070
Corsair Vengeance 32gb (16x2) 3.2Mhz
Corsair RM 750 PSU

The problem:
When I turn off the PC/sleep and turn it on soon after it works without a problem. However, if I leave the PC off overnight, hitting the power button causes it to turn on for a split second before turning off (doesn't reach POST). If I unplug the PC from the main power supply and drain the capacitors it works. While the PC is on I do not have any issues.

What I have tried:

• Making sure all connections are secure, including but not limited to PSU connections, GPU in mobo, and RAM being securely in place.
• Replacing PSU. I was trying to use my old PSU (CorsairHX850i) for this build but with this issue I wanted to see if the new PSU would solve the problem. With the old one, the PC would not turn in even immediately after I shut it down. With the new one, it only does this after longer periods of time.
• Updated BIOS and tried this at default settings and when turning off CPU fan monitoring (I read this setting could cause startup issues with water cooled systems)

My next step is to replace out the motherboard but in the meantime I wanted to see if I could get some input whether I'm on the right track or not.

Thanks in advance!

 

[logainofhades]

See if there is a bios update, for the motherboard.

 

[Ralston18]

Did you mix and match in any cables from other PSUs?