PC keeps crashing when playing games.

[RossJK1]

Hi guys I just recently upgraded my PC with new parts (i5 9600k, RTX 2070 super, 16GB DDR4 RAM and gigabyte z370p d3 motherboard. However after playing games (forza 4, battlefield 1, witcher 3) for a varied amount of time the game will crash and so will the computer itself which requires me to turn it off and on. However the game runs perfectly fine.

The PC boots fine, all the fans spin, the temperature for the i5 sits at around 28 Degrees idle to around 45 Degrees underload and the GPU sits at 30 degrees idle to at max 68 degrees under load.

Ive made sure windows is at the most recent update, the geforce drivers have been uninstalled and installed again and all the drivers from the motherboard disk have been installed.

Im confused on what it could be? Perhaps my HDD, its almost 6 years old now and this is where my games are stored so that might be the issue?

Or the PSU its also almost 6 years old now. (Corsair 750M)

Any help is greatly appreciated!

[Zmax]

Could be heat related . Try a heat monitoring software. Many of then are free.

[RossJK1]

I dont think it is heat related as I said the highest the CPU hit was around 45 degrees and the highest the GPU hit was 68 degrees. Aren't these fairly acceptable temps?

I was using coretemp to measure the CPU and GPU-Z for the GPU.

[Zmax]

Oops, sorry mist the part about temp.