Not all CPUs are created equal
 

WHEN AMD INTRODUCED the Athlon 64 FX-55 and the 4000+, the company issued a press release that presented the introduction of an improved technique of Silicon on Insulator (SOI). The improvement carried the name Strained Silicon on Insulator (SSOI). The processors in question received rave reviews about its overclockability only using air cooling. Most FX CPUs worked on clocks such as 3.0 GHz with no problem, even if only retail, double-heatpipe cooler was used.