Computer randomly shutting off (not PSU)

[Tymmy]

So every few hours my computer will shut off randomly without warning then restart without me pressing anything. Afterwards I get no warnings or error codes. It's very irregular shut downs as well. I've had it shut off during 3d modeling/rendering, video gaming, and Internet surfing on chrome. Even once while totally idle while I was out of the room making lunch with no programs running.

 

The most interesting thing is I have a fan speed controller that has a clock and each time it gets reset as if the PSU was unplugged.

 

But it's not a bad PSU.

 

I swapped the PSU with another from a friend (same wattage, no issue with his PC) and I have the same issue. I also swapped the power cord.

 

I have tried on and off a backup battery (ups) and had the issue with both, so it's not wall power.

 

So I've ruled out power delivery.

 

I have a CPU GPU liquid cooled setup that runs around 40c even at time of shutdown so it's not temperatures.

 

It's happened while at stock speeds and overclocked, so it's not because of overclocking instability. (I can run benchmarks just fine)

 

There's no leaks and no mixed metals in the system. So it's not the liquid cooling system.

 

Any ideas what's going wrong? Cus I'm kinda stumped. The problem started about 2 weeks ago. System was built in 2014 with only a change of the liquid in the system and the diagnostic PSU swap. I've added more HDDs and SSDs since it was built but that's the only hardware change but nothing added recently, and none are acting up.

 

Windows 10

ASUS RAMPAGE V EXTREME

Intel 5960x

2x EVGA 980 SC

SAMSUNG XP941 for the C drive 

CORSAIR Vengeance LPX 16GB (4 x 4GB)

2x D5 pumps in series with full EK rads and blocks

 

The 2 power supplies I've tried are:

Rosewill RBR1000-MS 1000W

And 

Corsair HXi Series HX1000i 1000W

 

I have to assume there's something happening that's tripping the PSU since that's the only thing that would reset the clock, but it's not a PSU problem, as it's happened between 2 different fully functional power supplies. Any ideas?

[PCGeek]

I would monitor the temps just in case.  I had that happen to me once and it was a flaky power bar.