Using Computer Last Night And It Just Shut Down. It Would Repeat Start - Shutdown

I was playing an online game with friends last night when my computer abruptly shut down. Upon trying to restart it just once, the power would come on, then off, then on, then off repeatedly.
I've had this computer for a few years. and I've had it shut down a couple of times in the past, I thought maybe I accidentally hit the power button on the keyboard.
Then a few weeks ago I noticed that my monitor screen would blank out for a few seconds, then come back.

System specs: Windows 10

Proccessor: intel i7 4790K stock speed

Proccessor cooling: NZXT Kraken X31 120mm Closed Loop CPU Liquid Cooling System (RL-KRX31-01)

Motherboard: Gigabyte GA-Z97x-GAMING 5

Memory Total 16GB : 2 of the following Dual Channel Kits = G.Skill F3-2400C10D-8GTX 8GB (2 X 4GB) DDR3 PC3-19200 240MHz TridentX series CL10 (10-12-12-31) Dual Channedl kit

Graphics Card: Two Gigabyte Geforce GTX 970 G1 Gaming GDDR5 Pcie Video graphics cards, 4GB

PSU: Kingwin 1000 Watt psu Model No. ABT-1000MA1S

The first thing I did was to clear the bios (it was set for quick start) then I remove everything including the graphics cards and used onboard graphics.

I booted it into bios so I could see the cpu temperature (around 45c) . I've been using the Kraken liquid cooling for the cpu and thought the pump went on it.

Then I booted it up into windows 10 without and problems, so I added one of the GTX 970 graphics card and booted it up, again no problems, so I rebooted into bios and the cpu temp was 52c. Is it strange that adding the GTX970 would increase the cpu temperature?

I left the bios to auto set for all the motherboard functions and I noticed that the vcore is 1.476v to 1.488v which seems kinda high to me.

I suspect the problem is the PSU. I know Kingwin is not a well known brand and I can't even find it available anymore. So I'm getting a Corsair 850 watt gold certified PSU.
Any thoughts on this and I have 2 questions.

So what's the normal vcore for the i7 4790K ?
and what's the normal operating temperature for the i7 4790K?

 

Well, my first thought was power. Though I would have suggested you borrow a PSU and see what happens before spending any money, I don't find fault in your plan to replace that Kingwin from the start.

There is no normal vcore. CPUs report what they want to the chipset. If your BIOS is set at the default settings, you are fine.

And there is no normal operating temperature either as there are many variables affecting the temps. These include ambient (room) temp, tasks being performed at the time, case cooling and more. However, as seen here, the max Tcase allowed is 74.04°C so you have lots of wiggle room.

 

That's good to know. Thank you.

 

I've had this happen to me recently. It was indeed my PSU. I've had it happen before too, with BSOD screens. In those cases, it was a bad RAM stick.

 

I've removed everything but the essentials and booted it up. I was even able to play some games for several hours without issue. However; I'll be getting a Corsari 850 watt psu today that I'll replace the present psu.Then I'll add back all the other peripherals.