My PC won’t turn on unless I turn off power

[greenbeast]

I have a similar issue. (ongoing trying to figure it out)
New build
asus dark hero viii motherboard
ryzen 5 processor
corsair aoi
32gb ram
1 tb ssd
windows 10

I can turn on computer 1st run and everything is working. (In bios I had to ignore cpu fan since I have aoi cooling fan. Have to set it up or it keeps going bios)
Everything is running and reading fine. Once I shut down through windows setting. I am unable to turn on through tower or motherboard (motherboard also has start button). I know there's power because the motherboard light is still on and the start button on motherboard is still lighting up.

I have to turn off power to whole tower with the power supply on/off switch to be able to start system.

What do you think could be the issue?

 

[wiyosaya]

How old are these PCs? I ask because I had a similar thing in the past. For my instances, the problem turned out to be the CMOS battery in both cases. If the battery voltage gets too low, it can keep the voltage on CMOS down - (in a badly designed system IMO) which will prevent the system from running properly if it runs at all.

If the systems are newer, perhaps the manufacturer of the MB had a batch of batteries that were about to cross their expiration date and installed them anyway.

Anyway, CMOS batteries are relatively inexpensive and this is an easy thing to check.

 

[greenbeast]

My system within 2 weeks built. Will double check the CMOS battery.

 

[DLBU1]

As it could be an old driver that doesn't like the way WIndows 10 shutsdown. Win 10 uses a hybred hibernate which means its not off when you turn it off. Its asleep. It saves files onto hdd that were open at shutdown and then saves a copy of running drivers into ram. This means on startup, it should just jump into action since things are already running... but this doesn't work well with drivers not written for the mode.

 

[Kshipper]

I heard there is some kind of issue with the standby power on certain PSUs. This has happened to me on more than one build I have done. I usually use Seasonic 80+ Bronze or Corsair CX power supplies and it happened to me on both PSUs when I was working on the machine on the bench (not in a case yet). I thought everything was OK so I delivered the machine but I had to take the machine back and exchange it for a new one. It was a Gigabyte B450M DS3H motherboard, 8GB Kingston Hyper X RAM, with a Ryzen 3 2200G CPU. Before I exchanged it, I had the customer purchase a nice Cyberpower UPS, but that made no difference. The machine would still 'Play Possum' several times a week. I switched it out for a B365 DS3H and an Intel I3 and all was good. The misbehaving machine is now my new bookwork machine and I just leave it on all the time and so far, so good. I never power down my machines anyways.