Question Computer boots intermittently

[shmu26]

When I press the power button on this 5-year-old Pentium II desktop, the button blinks a little, but the computer doesn't turn on. At least, most of the time.
When the symptom first appeared, I thought the PSU was dead, and I put in an old PSU I had lying around. That helped until the next morning, when it stopped turning on again.
After waiting 24 hours, and throwing away the extension cord I was using, it booted again.
But this morning, same issue: the power button blinks but the computer doesn't boot. No sound from the BIOS or anything. No fan, no nothing.

 

[Vic 40]

With an old pc might it alos be usefull to replace the motherboard battery. Leave a little time in between so cmos gets reset as well. After that do get into the bios and make sure time and date are set correctly.

 

[shmu26]

I tried to start it by placing a screwdriver on the pegs that the power button connects to, and also on the pegs of the reset button. The fan turns over lazily for a few seconds and then dies again.
Removing the CMOS battery, and putting it back in a minute later, didn't help. I assume the battery is good because the computer keeps time even though it is never connected to the internet.