Question PC will only boot up sometimes, what could cause that ?

[Passels]

So I have an older computer I've been trying to get working after not using for about 6 months.

It sometimes boots up and runs apparently fine, no abnormal temperatures, running as fast as I'd expect. Its only able to turn on properly one in every 8 times though. The other times, fans and lights turn on, but no other signs of life.

I've torn it down as much as I can to try and isolate the issue, down to only the CPU, motherboard, one stick of RAM (it only has one) and CPU fan. I don't have the drives connected but pretty much the same issue happens trying to power on into the bios, sometimes it can get there, but most times not.

Tried a different PSU and different RAM, both known to be working in a different system, and the same still happens. Also tried new thermal paste and reseating all the remaining cables.

The only other things I can think to do are reseat the CPU and try taking the motherboard out of the case to test it (not sure if I'm grasping at straws here). I'll attempt these tomorrow.

So my question is, what else could I be missing? If the problem persists I'm comfortable deciding its time for an upgrade, but if there's an easy fix that would be nice.

CPU is an i5-6500, motherboard is an ASUS B150m-a.

Not sure if the other components are worth knowing about but its using an EVGA supernova 750w, also tested with a corsair rmx750, 8gb stick of no name ram, tested with corsair vengeance rgb DDR4.

 

[helpstar]

replace the BIOS battery
could be a bad motherboard (bad caps)

 

[Passels]

replace the BIOS battery
could be a bad motherboard (bad caps)

Unfortunately no luck with the new battery but thankyou for the suggestion, I'm surprised I didn't think of that.

I've now also tried taking the motherboard out of the case and reseating the cpu, still getting the same behaviour. Is it time to write stuff off?

 

[Passels]

So I have an older computer I've been trying to get working after not using for about 6 months.

It sometimes boots up and runs apparently fine, no abnormal temperatures, running as fast as I'd expect. Its only able to turn on properly one in every 8 times though. The other times, fans and lights turn on, but no other signs of life.

I've torn it down as much as I can to try and isolate the issue, down to only the CPU, motherboard, one stick of RAM (it only has one) and CPU fan. I don't have the drives connected but pretty much the same issue happens trying to power on into the bios, sometimes it can get there, but most times not.

Tried a different PSU and different RAM, both known to be working in a different system, and the same still happens. Also tried new thermal paste and reseating all the remaining cables.

The only other things I can think to do are reseat the CPU and try taking the motherboard out of the case to test it (not sure if I'm grasping at straws here). I'll attempt these tomorrow.

So my question is, what else could I be missing? If the problem persists I'm comfortable deciding its time for an upgrade, but if there's an easy fix that would be nice.

CPU is an i5-6500, motherboard is an ASUS B150m-a.

Not sure if the other components are worth knowing about but its using an EVGA supernova 750w, also tested with a corsair rmx750, 8gb stick of no name ram, tested with corsair vengeance rgb DDR4.

I'm noticing that I'm able to get it to start up, turn off, then turn back on again fairly consistently, inbetween these the motherboard has an orange breathing light on it. But if I turn the power supply off and unplug it, then turn it all back on, it goes back to not starting back up, and of course the orange breathing light goes off inbetween. Is this possibly useful for diagnosing the problem?

 

[helpstar]

check the cpu socket of the motherboard for bent pins

 

[Passels]

check the cpu socket of the motherboard for bent pins

All seems to be in order with the pins after a good look from a few angles.

I ended up deciding to update the bios, which was probably risky given the instability, but it seems to actually have fixed things. It hasn't failed to boot once and now it's a lot faster at booting too. Fingers crossed it stays fixed.