[Solved] PC starts then instantly turns off

[divyangpradeep]

I assembled my first pc about a month ago, and everything was working fine (liquid cooled 8700k oc'd to a stable 5ghz at 1.3v). Today I tried turning it on, and it instantly turned off. Since it did double boot at times, I thought it will turn on again, but that didn't happen. At the moment it starts the board posts 00 (manual says it stands for "Not Used") and then instantly turns off.

Last time I used it was day before yesterday, and experienced no issues.

Since then I've tried -
a) Clearing CMOS with clear CMOS button and removing CMOS battery for few minutes (doesn't seem to work since the motherboard led didn't revert back, and is what I set in ASUS Aura)
b) Updating bios using ASUS USB BIOS flashback.
c) Removing and reinstalling all the components.

I think only thing left is trying a different PSU/CPU but both are difficult as I only have a laptop other than this build.

Any help regarding this would be appreciated, because I can't figure out what could make the system not start after working perfectly fine all this time, and there were no power surges/failures etc too. Really puzzling since nothing had changed since last time it was powered up.

Specs
i7 8700k (stable oc to 5ghz, 1.3v)
ASUS Maximus X Hero
Corsair Vengeance LPX DDR4 3000mhz 1x16gb
H115i AIO liquid cooler
Samsung 860 evo 250 gb ssd
Corsair TM850X PSU
AOC AG241QX (1440p 144hz)
NZXT S340
No dedicated graphics card, using integrated graphics (waiting for benchmarks on rtx)

 

[ameyer75]

When clearing CMOS, unplug the computer, remove the battery and hold the power button for a solid 10 seconds. If that doesn't fix it, then I would suggest you are correct in assuming it's either your CPU or PSU. The PSU is the easier (and cheaper) one to replace, so start with it. If that doesn't fix the issue, you can always return it. Then do the same for the CPU.

 

[divyangpradeep]

When clearing CMOS, unplug the computer, remove the battery and hold the power button for a solid 10 seconds. If that doesn't fix it, then I would suggest you are correct in assuming it's either your CPU or PSU. The PSU is the easier (and cheaper) one to replace, so start with it. If that doesn't fix the issue, you can always return it. Then do the same for the CPU.

I tried doing that, no difference. The motherboard I have has lighting effects even when turned off (psu plugged in and switched on), so that should reset when clearing CMOS, right (default is rainbow but I set a breathing red effect, and it hasn't changed from red all this time)? Also, the clear CMOS button on I/O shield is lit, is that okay? Shouldn't it be off if nothing is happening?

If I can't figure it out, I might just have to take it to some hardware store. I should still have no trouble having any component replaced under warranty, right (the cpu is my main cause of concern cause it's the most expensive part and Intel could say warranty void due to overclocking) ?

Because buying any of these again is really out of my budget. If I had a sure way of knowing what's wrong, I could start the process of replacing it.

 

[divyangpradeep]

In the end I took the mobo for RMA. The process was a week long and then I got another one. Had to spend an entire day battling with various qcodes but in the end it started working. The issue seems to have been shorting in the board somewhere because I had no no grounding at my place. Called an electrician and he did some stuff, things are working fine now.