The answer as to why its only happening in d3 for your computer is not easily given.
In general stuff is more complicated than just saying its taxing on cpu/gpu thats why its crashing.
It can be something very tiny detail like d3 executing a certain directX API function which only a few other games (you do not play) use. this function might use a lot of power on the gpu and then it fails because your PSU cannot deliver this spike . (this is just an example)
but in general the hint is correct, something is not correct with your hardware.