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

Usually happens every 3 times I boot it up. Does this sound like a mobo issue or PSU issue?

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. I tried removing the 8gb new ram, but still have the problem.
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?
Reply to UCFTyler
2 answers Last reply
More about turns minutes shuts turns back automatically runs fine
  1. Try this sequence:

    1) issue may be RAM - take out your new RAM and continue from step 2.
    2) isssue may be GPU - take out GPU and try booting from integrated GPU of your CPU by connecting monitor to motherboard's monitor ports. Wait if the problem occurs.
    3) If problem occurs, do a CMOS reset, BIOS update etc etc. Try again.
    4) if you do not see any problems, try putting your new RAM in. try booting from IGP again. Wait if the problem occurs.
    5) if problem occurs, you have incompatible RAM for sure. Change the new RAM with a compatible one.
    6) if problem not occurs, the problem is with your GPU. What it is I don't know. You might try updating your drivers etc.

    Trying the combination of 8 GB original RAM + GTX 1070 will not help you at all; not because you have already tried that, but it is a formula for calling disaster installing a 8 GB GPU on a system with 8 GB RAM. This point is s long discussion, but is not relevant for you at this moment.
    Reply to eyupo92
  2. The obvious answer is always the PSU and then the motherboard. But sometimes the obvious answer isn't the right one. I was having a similar issue. It started out on a graphics intensive game, it would just just down randomly and reboot. Then it would run fine and do it again, only on intense programs. My GPU was below specs, so I upgraded that. I replaced the PSU. I did tests on my memory. Really all that was left was my motherboard. I had the case open and started it and was just looking in there and I heard a slight rattling. Turns out, my CPU fan was going bad and was causing all my problems.
    Reply to Bo Lee
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