Issue with my new build. Is my gpu faulty?

[MAUROE]

I am having gpu issue with my first pc build. Gpu runs great when I first start a game but after around 40 min to an hour of gaming the fps drop drastically and bounce around. Fps will drop from 60 to like 1 and bounce around to like 10 and back down to 1. The games become unplayable and it becomes hard to exit out. I don't get any error message or pc shut off. Temps seem stable. Gpu at idle is around 40c and at full load will be around 60c. Cpu idles at 32 and will go mid 40c at load. I will launch a different game after the issue to see if the game is causing the problem and the new game will stutter also at launch. What could I do to check if the gpu is faulty?

Pc specs
Asus strix GTX 970
Mobo Asus maximus hero viii z170
16gb ram
PSU Cx 750w
Cpu Skylake I5 6500
Hard drive Evo 850 250gb +
1tb hard drive
Cpu cooler hyper 212 evo
Windows 10

 

[neatfeatguy]

I'd suggest running GPU-Z in the background while you're gaming.

Under the sensors tab you should see the readouts for GPU load, temp, memory usage and so on.

When you hit the point during your gaming where things slow down, ALt+TAB out of the game or exit out and look to see what the GPU Core and Memory Clock was showing when things slowed down. If you see a sharp drop in the graph line, then for some reason the GPU is clocking down.

It could be throttling due to temps, so you can also see what the temp was at when the game started having issues.