Boot loop and random power loss

Night_Wanderer · March 12, 2017

Hi all,

So I built a custom PC a few months ago and it was working perfectly up until this week, when it suddenly started having some odd power and boot issues.

So here's what happened. I was using the computer as normal just surfing the web, when all of a sudden it turned off. No error message, no blue screen, nothing. Instant power loss. After a few seconds, it automatically tried to boot up again, all the fans started to spin up, lights came on, and then it shut off again. It was just stuck in this cycle of trying to turn on and failing.

My first thought was that its an issue with the power supply, but i doubt that's the case since all the components were still receiving power, just the PC was unable to boot. Then, I noticed a red light on the motherboard, labelled CPU_LED. Looking at the motherboard manual, there seems to be no explanation as to what that led actually means, but I'm assuming its some sort of issue with the CPU.

Anyway, after a while of being stuck in this boot loop, it somehow managed to break out of it, and the system managed to POST, but, it showed a BIOS error saying "Overclocking failed. Please enter setup to re-configure your system". Note that I have NEVER overclocked anything in this system. Everything was running on stock settings. Even XMP was disabled. So after getting into the BIOS, I set everything to default, rebooted, and the system started normally this time. Strange, I thought, so I ran some benchmarks, stability tests, and everything was running fine. But then, after some time, it happened again. Same instant power loss, same boot loop, and same red CPU_LED on the motherboard.

At this point I did a tonne of searching on the web and tried everything from re-plugging all the power cables, clearing CMOS, booting with only one RAM stick at a time etc. But despite everything, the same problem still occurs. The system cannot stay on for more than an hour. Sometimes it turns off in 15 minutes, sometimes in 50 minutes, it seems to be completely random. Though strangely, the problem has never happened while running a stress test. Go figure.

So I'm thinking at this point that it must be some hardware issue, with either the motherboard, CPU or power supply, but unfortunately I don't have any spares to test with further.

Form what I've read online of people having similar problems, there seems to be no definitive answer as to what could be causing this.

The system specs are:

CPU: Intel Core i7 6850k
GPU: 2 x Nvidia GTX 1080
RAM: Corair Vengeance LED 32GB DDR4
Mobo: Asus X99 A-II
Storage: Intel 256GB NVME SSD, Samsung 500GB SSD, Seagate 3TB HDD
PSU: Corsair AX860i
Case: Corsair Obsidian 750D
Fans: 6 x Noiseblocker e-loop (b12-ps)

Here are some screenshots of the system running stability tests and a short video of what's happening.

Any help would be much appreciated,

Thanks

19_blackie_73 · March 12, 2017

First thing I'd try is swap the psu, its the easiest thing to test

After that my guess would be mobo, its very unlikely that a cpu dies especially if you didnt oc it

Enderman · March 12, 2017

Check windows event viewer to see why it shuts off?

Night_Wanderer · March 12, 2017

33 minutes ago, 19_blackie_73 said:

First thing I'd try is swap the psu, its the easiest thing to test

After that my guess would be mobo, its very unlikely that a cpu dies especially if you didnt oc it

That's what I thought as well. Sadly I don't have another one at hand. I'll ask around at work tomorrow see if anyone has a spare. It's quite strange though the way it works for some time and then loses power.

19_blackie_73 · March 12, 2017

1 hour ago, Enderman said:

Check windows event viewer to see why it shuts off?

Check This^^

27 minutes ago, Night_Wanderer said:

That's what I thought as well. Sadly I don't have another one at hand. I'll ask around at work tomorrow see if anyone has a spare. It's quite strange though the way it works for some time and then loses power.

Yeah sometimes pcparts are a bit strange, but it's worth a try

Maybe order a new one and send it back if it does not change anything

Night_Wanderer · March 12, 2017

1 hour ago, Enderman said:

Check windows event viewer to see why it shuts off?

These are the only errors I can see. I think the second one is to do with Intel Virtualisation technology which is disabled in the BIOS by default. Enabling it makes no difference.