2.9 GHz Or "roughly" One Athlon64 FX 58
The Asus board indicates the processor temperature below the freezing point.
The Athlon64 FX fundamentally differs in one point from other available processors: The user can freely choose the clock multiplier (assuming the motherboard allows this). The multiplier is the factor that determines processor clock speed:
While a 3.2 GHz Pentium 4 operates with a multiplier of 16 (multiplied with 200 MHz system clock rate, you get 3,200 MHz, or 3.2 GHz), the Athlon64 FX can be operated with clock rates other than 200 MHz times 11 (2.2/2.4 GHz - FX 51/ FX 53).
That, in turn, translates into an interesting feature for speed freaks, as most processors offer an overclocking potential of only up to 15%.
The Athlon64 FX was unstable at 3 GHz, so 2.9 GHz is the best clock speed the processor can offer.