Question Custom Built Problem Diagnosis

[xenosaga01]

Hoping you smart people can help me out, I helped a friend build a custom desktop. He picked the components, I helped him assemble and install OS and updates. The System has the following components:

nzxt case
asrock z270 killer sli/ac
Intel core i5-6700K @3.8ghz stock 4.2 turbo
Coolermaster Hyper 212 evo cpu cooler
Corsair dominator DDR4 2x4gb 2133mhz ram
Thermaltake Smart 700Watt 80+ white certified PSU
Kingston a400 128gb 2.5” ssd(boot drive)
Western digital 1tb 3.5” hdd(storage drive)
It has a zotac GeForce gtx 1050ti 4gb
It’s running Windows 10 Home 64bit.

This system ran perfectly fine for 2 years, no crashes at all. Thermals were perfect. 35-40celsius at idle and 65-70celsius during hard gaming or high load. His system had a blue screen while playing Rust and right before it happened he noticed his ram was almost all being used. So he bought new ram. He chose Corsair Vengeance LPX 16GB 2x8GB DDR4-3600 ram which is compatible with his motherboard.He installed it himself and upon looking at CPU-Z determined that the ram was still running at 2133MHZ.

I came over to help him get the ram running at full speed and was able to achieve that by setting the XMP 2.0 profile and changing it from auto to 3600. It worked fine for 2 days and then he started having really slow boot times and then shortly after loading the desktop the computer powers off. pretty much every day since I’ve been trying to help him, his computer has gotten worse and to the point that when it attempts to load into Windows, after about 1-2 minutes, the system fully shuts off(no warning or blue screen at all) then reboots in about 15 seconds automatically.

I reset the motherboard to defaults and the ram back to 2133MHZ and no change. We even tested the ram with memtest86 and it passed all the passes with no errors.

We also removed the new ram and put the old ram back in. No change. The computer still cuts out about a minute after loading windows. No errors or blue screens, it’s as if the power switch is switched off.

I’m guessing at this point it’s either power supply or motherboard and leaning closer to Power supply. Another thing I noticed is that the CPU voltage was fluctuating right before the system turns off. It was ranging from 0.808v-1.2v. All temps normal.

the motherboard has no logs and we can’t boot long enough to see if there are any eventviewer logs but I’m guessing since there are no blue screens that’s it’s more a hardware issue. Please offer me any advice or confirm if my assumptions are correct.
My friend has ordered a new PSU to try to see if it is in fact the PSU causing the issue. I don’t think there is any way to test the motherboard.

 

[xenosaga01]

This can be closed. Was caused by the GPU strangely enough. Swapped it to the second PCI express slot and it works fine. But the ram at 3600MHZ triggers ntoskrnl missing or corrupt and a pci.sys missing or corrupt error in Windows 10. Dropped it to 3000MHZ and it’s stable and boots without issue.