PC turns on for a few minutes, shuts down, turns back on, then runs fine

[UCFTyler]

I can usually make it past the windows login screen for a few minutes before the problem happens. The problem usually happens every 2-4 times I boot it up, and after it has shut down and turned back on, it never has the issue again and I can use the PC for as long as I'd like.
All hardware tests come back good, CPU, GPU, RAM, HDD's and SSD, and temperatures are fine.
What is it? I've tried refreshing windows 10, taking out the new memory I put in, getting all the dust out, new surge protector, battery backup, and no fix.
I recently put in a new GPU (GTX 1070) and added 8GB of additional RAM to now have 16 just a few days before the problem started, but like I said, tests show they are OK.
GTX 1070 GPU
MSI Z97 GAMING 5 MOBO
I7 4790K CPU
CORSAIR 750W PSU
8 GB + 8 GB GSKILLS RIPJAW RAM

I RMA'd my PSU for a replacement from Corsair, does this tend to happen when a PSU is possibly faulty? If it isn't the PSU, it's gotta be something with the mobo, right?

 

[Barty1884]

It could be the PSU (which PSU specifically?), but given it stems from your upgrades - I'd look there first.

If you remove your additional 8GB RAM, does the issue persist? Not sure if you meant you'd removed & tried, or whether you just removed/reseated.

Did you fully remove your prior GPU drivers? Run DDU in safe mode: http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

How do things look after that?

 

[UCFTyler]

It could be the PSU (which PSU specifically?), but given it stems from your upgrades - I'd look there first.

If you remove your additional 8GB RAM, does the issue persist? Not sure if you meant you'd removed & tried, or whether you just removed/reseated.

Did you fully remove your prior GPU drivers? Run DDU in safe mode: http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

How do things look after that?

Removed and tried with the original 8gb ram, still shut down about the 3rd boot up.

Can't remember if I removed my old GPU drivers or not (started happening about two months ago). Can't test since I shipped my psu back to Corsair for a new one already. I remember when first troubleshooting the error removing/updating a bunch of drivers, and I think I did remove it, although not 100% sure. Wouldn't a driver issue cause the BSOD and not a complete power loss?

There's also been two instances in the past where it shut down and didn't automatically come back on for a few minutes.

 

[Barty1884]

Driver conflicts can cause a bunch of different issues - for no apparent reason. I'd agree, BSOD would be more likely, but stranger things have happened.

Shutting down and not returning for a period of time could be PSU related.
Could also be temperature related (CPU/GPU/Mobo/potentially even PSU).

 

[UCFTyler]

It could be the PSU (which PSU specifically?), but given it stems from your upgrades - I'd look there first.

If you remove your additional 8GB RAM, does the issue persist? Not sure if you meant you'd removed & tried, or whether you just removed/reseated.

Did you fully remove your prior GPU drivers? Run DDU in safe mode: http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

How do things look after that?

Driver conflicts can cause a bunch of different issues - for no apparent reason. I'd agree, BSOD would be more likely, but stranger things have happened.

Shutting down and not returning for a period of time could be PSU related.
Could also be temperature related (CPU/GPU/Mobo/potentially even PSU).

Praying that it is a bad PSU, just want this thing solved already. I've literally had dreams where I'm using it and it shuts down, that's how crazy in going. I've run the PC under stress and played some fairly graphically demanding games and it doesn't happen then, usually within minutes after initial boot up to the desktop every 3-4 times I turn the PC on. Sometimes after 1 minute, sometimes an hour.