Pc turns off while gaming

[RichMane]

when im playing games my pc turns off for a moment and then turns itself on again.
i've had this pc for almost 2 years now and this problem has only occured for 1 month or so.
I already checked my CPU and GPU temperatures while im running games and my temperatures are normal. CPU is around 50 - 45 C. GPU is around 70 - 80 C
I've also done a full scan on my computer. Avira found 3 virusses; one being adware the other two were TR's but those are likely to be false positives bcs they are cracks.

specs are:

i7 5820k
gtx 970
16 gb ram
111gb ssd
2 TB hdd
750 W power supply

 

[Isokolon]

mm what kind of PSU do you use and how old is it?
might not be up to the task anymore

 

[RichMane]

mm what kind of PSU do you use and how old is it?
might not be up to the task anymore

its a coolermaster g750m and its also 2 years old

 

[RARRAF]

sounds like a dieing PSU from what I can see

 

[RichMane]

I forgot to mention something. My pc only shuts down when im playing games like overwatch, rocket league or the witcher, but for some weird reason it doesnt power off when playing NFS 2015. I don't know if this helps but I thought i'd give you guys extra info.

 

[RARRAF]

its your graphic card demanding more power and the PSU is not suppling it and wierd stuff happens

 

[RichMane]

its your graphic card demanding more power and the PSU is not suppling it and wierd stuff happens

But thats weird bcs i can run NFS with no problems
Also i could play overwatch today with no problems until i came back to the main menu. My pc then turned off.