I've never messed with CPU coolers before in builds, figuring the stock Intel cooler should be sufficient since I don't overclock. But, having noticed my CPU temp peaks at around 63-65o C during AH, I thought I'd look into trying one out. Normal no-load CPU temp for my I5-4590 is around 37-38o.
I picked up a CoolerMaster Hyper T2 from NewEgg for $10 after rebate, and jut got it in and tested. My CPU running AH dropped 20o, down to 43oC and my no-load temp dropped to 30o. Coolers can run near $100 but after this I'd have to say even an inexpensive cooler makes a big difference.