Yeah. I OC' it to 1300MHz and the memory to 1686 with +7%power. Is it good? I still need to check the max core speed, and then test everything again with the memory
the gpu overclock run her hotter then you play game that ask more power so she could be cutting from overheathing so reduce the gpu overclock to normal settinngs then try the game after redo the overclock a notch at the time until it cut off .
74 degrees is quite high for gaming. My OC'd R9 270X never goes above 60 degrees when playing any game. Try lowering your voltage or over clock and see what happens.
this will help reduce your temp try with the factory voltage and use the amd ccc to ajust the clock speed on the gpu and memory clock try the auto ajust settings .