If you've swapped out a CPU or replaced the CPU+motherboard then stability testing might not be that important. If you've put together a complete new build then I'd suggest that you put the system through its paces just to make sure that everything is working as it should.I have an intel core i7 4770k and I'm not overclocking it at the moment. My idle temps are around 28 degrees Celsius. Is it still necessary to run a program like prime95 and stress test my cpu even though I am not overclocking?