I've got a home built computer that I put together in 2011 that has the CPU overheating again. The last time this happened a couple of years ago I just replaced the thermal paste and that fixed it. This time, that's not good enough, and I think I need a new CPU fan. My question is, should I just get a better fan, or would it be worth it to replace my Athlon II 640 Propus quad core CPU with a Phenom II? If so, would a phenom X6 be a lot better than a phenom X4? My ASRock 890GM PRO 3 motherboard supposedly supports both. I'm running windows & 64 bit home premium with 8GB ram. Any thoughts?