Pc wont reach post, reboot loop every 2-4 seconds.

[Darkesthours838]

Dear smart people,

 

Yesterday evening I restarted my PC (I rarely do this, maybe once a month, the machine is on 24/7) after which it keeps power cycling after 2-4 seconds.
What I mean with this is, I press the power button, the fans start to spin, the lights turn on, the hdd's start spinning, however after 2-4 seconds the power cuts off. 
It's quiet for a second or 2 and it will attempt to try it again, only to meet itself in an endless loop until i either hold the power button or pull out the power cord.

 

So, no post, no bios, none of that.
What's strange however is that the lights that are embedded into the motherboard, sometimes DO light up, and sometimes they don't light up within those first couple of seconds after pressing the power ON button. (Normally the embedded motherboard lights should always be on if the system is powered on)  <- the way to reproduce this, the embedded lights not turning on, is simply by unplugging the 8 pin CPU power connector. It might mean nothing, i just figured it might be usefull info.

The core system has run for about 5 years now without any issues or trouble whatsoever, i've only upgraded the perhiperals and the GPU a year ago.

 

Gigabyte Ga-Z97-HD3 Rev 2.1 - Bios F9
i7 4790k

Two 8GB DDR3-1600 Crucial (identical so they have proper timings for dual channel)
Psu; Corsair CX650

 

What I have tried so far to exclude a couple of things;

 

- Cmos bat swap with a fresh one, aswell as the Cmos Clear jumper.
- Checked every single cable if it was plugged in securely.

- Unplugged all the "extra" hardware like ssd's and the GPU so that just the mobo, cpu and ram were powered by the PSU

- Tested the PSU in a compleet seperate system (PSU is fine)

- Pulled out the RAM sticks en swapped them with each other's slot (no luck), however when I tried to boot with just one ram stick the system suddenly reached POST en showed me the bios screen, this however I have not yet been able to reproduce after about 50 times of swapping the ram sticks around in the different slots and what not. 

 

Conclusions I've made so far; Since I managed to reach POST once after messing around with the Ram makes me suspect it's Ram related, however after not being able to reproduce it and having not been able to reach POST again is weird because having both Ram sticks fail at the same time seems weird to me. Which brings me to the motherboard itself?



Would love to hear if somebody knows anything I can try!

[Sjaakie]

Sounds like a motherboard failure indeed. Especially when testing the ram sticks seperately and they both won't post. And the psu has been tested and working.

 

If this other system that you have tested the psu in has some compatible components you could use them to troubleshoot further. A socket 1150 motherboard would be best, but if it has ddr3 ram you can try those to make absolutely sure its not the ram.

 

[Darkesthours838]

11 minutes ago, Sjaakie said:

Sounds like a motherboard failure indeed. Especially when testing the ram sticks seperately and they both won't post. And the psu has been tested and working.

 

If this other system that you have tested the psu in has some compatible components you could use them to troubleshoot further. A socket 1150 motherboard would be best, but if it has ddr3 ram you can try those to make absolutely sure its not the ram.

 

Sadly the other system is a socket 775 with DDR2.

 

Are there any motherboard "quirks" that might cause it to behave in this matter? 
Like which specific part on the motherboard would one most likely point to.

 

[RollyShed]

2 hours ago, Darkesthours838 said:

Are there any motherboard "quirks" that might cause it to behave in this matter? 
Like which specific part on the motherboard would one most likely point to.

 

I had a year ago, a capacitor fail on my motherboard and the computer would drop out intermittently. Look for any with a bulged top. I presume you know what a capacitor looks like?

[Darkesthours838]

35 minutes ago, RollyShed said:

I had a year ago, a capacitor fail on my motherboard and the computer would drop out intermittently. Look for any with a bulged top. I presume you know what a capacitor looks like?

I've given the mobo a couple good look overs now with a flashlight, all of the caps seem to be solid caps on this particular mobo so no bulging.
All of the caps like similar to the ones in the picture.

Also looked around for discoloration, nothing except some dust build up here and there.

 

[Darkesthours838]

After leaving the system for about 15 minutes in it's reboot loop I came back to it greeted by the windows 10 start up logo with the text below it " Getting your devices ready ". Sadly it seems it freezes up when it gets to this.

Pressing the reset button on the front of the PC does restart the system (altho it goes back into it's reboot loop) which does seem to hint at that it hasn't completely frozen up the entire system?

Seen the "getting devices ready" screen about 3 times now, everytime with the same result.

Inserted a bootable win 10 usb stick to try and get to the repair menu since my bios is set up in such a way that it'll always boot from a bootable usb whenever one is inserted it succeeded after leaving the system in it's boot loop for another 15-20 minutes.

This time I am greeted by a purple background, which I remember from the installation UI, however the system freezes up again similar to the "getting your devices ready" freeze.

So, TLDR; 
Managed to get the mobo to POST once in every ~200 boot attempts,
Managed to witness a POST once, and spam pressed the DEL key, which brought me into the BIOS.
Browsing the BIOS gave zero issues, aswell as everything inside the BIOS itself seemed to be proper, it found all the connected drives, it reported both ram sticks, etc.
After closing the BIOS however it got back into it's reboot loop.


Question that remains I guess would be, what would cause a system to freeze up once it attempts to load in core windows files, but at the same time browsing the BIOS would not give any issues/causes.

My suspicion of a faulty mobo keeps growing.