Computer suddenly shut down and won't turn on again

[Or Aviram]

About a year ago I posted here about a problem my computer had:

 

 

TLDR: my computer could rarely turn on. It would usually attempt for a little, and then turn off, then try again, sort of like boot looping (but nothing ever showed up on the monitor). After enough attempts (and a few random things to increase the probability) it would sometimes work, and, after I got it on, it worked with no problems.

 

Since that thread my (pretty bad) solution was to just not turn it off. From time to time I did turn it off, and when turning back on it somehow worked perfectly. I never tried sleep mode, which was the most problematic, though. When restarting it always worked, that was also the case in my old thread. Even when there was a power outage which caused it to unexpectedly shut down, when power came back it could turn on smoothly.

Still, it sometimes stayed on for months at a time.

 

Today something changed: suddenly it turned off. Just like I turned it off, nothing suspecious, but I wasn't the one who did it. Now it won't turn back on again. And in an even worse way than from my precious thread: clicking the power button now doesn't do anything.

(The incident happened while using mGBA for the first time ever, so it could be related but I don't see any reason for it to be.)

 

I did basic things like disconnecting the power cables and trying again, and also some of the solutions that sometimes worked in my old thread, but nothing worked.

To check if maybe the problem is in my case I tired turning it on by jumping the power pins on my motherboard with a screwdriver but it didn't work (no idea if I did it right, though).

 

I doubt the PSU is the problem because the power LED on my motherboard is on whenever the PSU is on. The GPU also lights up when turning on the PSU.

It's probably the motherboard or CPU, that's the guess, but I'm open to more ideas.

 

Last thing I'll mention, that could be the thing... An idea I came up with in my old thread is to replace the CMOS battery on the motherboard. I bought a new one but ended up not switching, mostly because I wad afraid of turning off my computer and not getting it on again. It's possible this is all I need to do.

Another thing to mention is that I put down cleaning it for the same reason and it had collected quiet a bit of dust...I doubt it's a big deal since some computers go years with no cleaning but maybe it's related.

So for now, if no one can help, the plan is to clean it and replace the CMOS battery, and if it doesn't work I'll buy a new motherboard and CPU.

Still, I'd love to hear more opinions.

Oh and I monitored the temperatures throughout the time my PC was kept on and there was nothing out of the ordinary. 

 

My system specs:

Asus Sabertooth X99 motherboard

i7 5820K CPU (not overclocked, base voltage)

GTX 1080

BeQuiet Dark Rock Pro 4 cooler

Corsair AX860i PSU

Cooler Master Mastercase Pro 5 case

 

 

[Or Aviram]

An update...

 

I cleaned my computer and along the way tried a bunch of things.

 

Replacing CMOS battery did nothing.

Replacing thermal paste did nothing.

Using less RAM sticks.

And my boot attempts were done only with motherboard, CPU, CPU cooler and case or screwdriver (tried both, in all attempts).

I also tested my PSU using the self test button and it seems fine.

 

I removed the thermal shield thing on my motherboard, and checked the components, and nothing seems to be bad (although I obviously can't know for sure just from looking). I also took my CPU out and both the socked and the back of it look fine.

 

It's weird that it just suddenly stopped working, and everything seems fine, but when trying to turn on no fan spins, it's like the power pins got screwed.

 

The only option I see now is buying a new motherboard and CPU but it feels so weird since the system should have lasted for longer.

I'd love more opinions on this!