Tom's Hardware- Since the birth of the IBM-compatible PC, a number of processors have distinguished themselves as particularly good candidates for aggressive overclocking. Some models are known for exceptional headroom, while others were popular for how inexpensive they were. We even remember a few unique opportunities to unlock on-chip resources that shipped turned off.
AMD Phenom II X2 550 And X3 720 Black Edition
the only AMD Cpus i ever respected, especially when you did the unlocks and still are good today for dirt cheap builds.