Top 10 Best AMD CPUS for overclocking.

AMD Athlon And Duron 600 (Thunderbird/Spitfire)

AMD's first-generation Athlon employed a cartridge that dropped into the Slot A interface, and its multiplier could be unlocked with a separate device called a golden finger tool. These processors were great overclockers in their own right, but in 2000, when the next-generation Thunderbird/Spitfire cores arrived in Socket A form, overclocking became a lot easier thanks to the famous L1 bridges.

All that you had to do was connect four little bridges on the CPU package with a pencil (or better yet, a conductive pen) to unlock the clock multiplier. An $80 Duron 600 could be overclocked to the 1 GHz range with nominal effort, coming close to Athlon 950 ($360) performance and pushing enthusiast-class speed under $100.

Similarly, the more expensive Athlons could be taken above 1 GHz at a time when top-tier Intel Pentium IIIs were relatively overpriced, if you could find them: 1 GHz+ Intel models were extremely rare for months after their introduction. Thunderbird's successor, Palomino, made the pencil trick obsolete, but not before the Athlon and Duron drew a lot of overclockers into AMD's sphere of influence.

AMD Athlon XP-M 2500+

After AMD locked down the multiplier on its desktop CPUs, overclockers realized how much potential the pin-compatible mobile versions offered. For a $25 premium over the desktop CPUs, mobile Barton processors employed a lower stock Vcore (1.45 V) and adjustable ratios. As a result, the Athlon XP-M 2500+ running at 1.83 GHz often made it as high as 2.5 GHz range with moderate tweaking. Some folks even took these processors to 2.7 GHz.

AMD Opteron 144
While AMD's Athlon 64 CPUs were great performers, they typically didn't facilitate tons of overclocking headroom compared to the Pentium 4. In 2005, though, AMD released the 1.8 GHz Opteron 144 for under $150. Opterons have always been business-oriented chips destined for servers and workstations, requiring registered memory. However, the 144 was a single-socket variant that dropped into Socket 939-based motherboards employing unbuffered DDR memory. Equally important, it was an incredible overclocker. Many samples were capable of hitting 3 GHz at a time when the highest-end 2.8 GHz Athlon FX-57 sold for $1000.

AMD Phenom II X2 550 And X3 720 Black Edition
AMD's flagship Phenom II was never an overclocking monster (effectively capping out in the 4 GHz range). But the company's Black Edition processors at least made tuning easier through access to unlocked ratio multipliers. The Phenom II X2 550 and X3 720 were extra special in that they contained disabled CPU cores that, in some cases, could be turned on using motherboards supporting this capability.

While some of these processors simply had defective cores that couldn't be resuscitated (making this a game of luck), a great many were able to operate as quad-core models, sometimes over 3 GHz. In 2010, when high-end quad-core Phenom IIs sold for $180, you could roll the dice for $100 and were often rewarded with a more premium-class chip. At worst, you had a dual- or triple-core CPU that could still be overclocked through its multiplier for relatively little.