Is my motherboard faulty ?

[ciolac.iulius]

Hello everyone, first of all I'm sorry about my english and the mistakes I'll make

The problem I have with my computer is that whenever I play a game that has high graphics, it shuts off immediately as if unplugged. Now I can still play some old games and such, but it's really bothering me.
I went to a PC-reparator, and they quickly looked at the problem, called and told me it was the GPU. I had a Geforce 980.
So today I received my new GPU, a EVGA Geforce 1070ti

My specs are :
CPU : i7-4790K @4.00GHZ
GPU : EVGA Geforce 1070ti
PSU : Seasonic Focus Plus 850W Gold
Motherboard : Z97 PC MATE
OS: Windows 10, 64-bit
RAM : 8GB DDR3
I built this PC in 2014, so everything is from then except the new GPU

So far I've already tried :- Putting the GPU on the other PCI slot
- Older drivers and/or reinstalling new ones for the GPU; updating the other drivers
- Running the games with the integrated graphic card, wich works, but as you except very slowly
- Switching between the different power cables that power the GPU
Also, I used OpenHardware to look at the temperatures the moment it shuts down, but neither the CPU nor the GPU go above 50 degrees.
- Cleaned all dust

Thanks in advance for your help


( EDIT : WRONG PLACE SORRY )

 

[NightHawkRMX]

Sounds like a faulty psu.