My PC is suddenly turning off

[LightMachineGun27]

Hi every one, this is my problem: Recently, I built this pc for my cousin. The same goes off at times without notice, other times while playing GTA V, I have not noticed if it does with the Rise of Tomb Raider or Mafia III
The specs are these:
CPU: i7 4790k, stock cooler
Mobo: GA-Z97X Gaming 5 Gigabyte
RAM: Corsair 2x8 2400MHz
GPU: GTX 1070 G1 Gaming
SSD: Samsung 850 EVO 250 Gb
PSU: Corsair CX 750 M
Sometimes when the table is moved, it also restarts.

Many thanks in advance for any help

 

[Dark Lord of Tech]

Is your PSU a CX with green lettering?

 

[LightMachineGun27]

Is your PSU a CX with green lettering?

yes it is

 

[Dark Lord of Tech]

Are all your power connections fully inserted including the PSU power cable.

 

[LightMachineGun27]

Are all your power connections fully inserted including the PSU power cable.

I have already checked it, it has happened to me before, but this is not the case

 

[LightMachineGun27]

The pc is taking me to the edge of madness, now it restarts sometimes when I execute light tasks, once it restarts, I run a stability test for more than 30 minutes without any problem, I run the GTA V, Mafia III, Rise Of Tomb Raider and all wonderful. When I turn it off for a few hours I turn it on again, it restarts it self in the slightest chance, but once restarted it does not happen again.