a very nice read, the fact is that the new FX/64 CPu's don't overclock much.
but same can be set of the first batch of Athlon XP's
my first Athlon XP1700+ did 1530Mhz.. max.. that is only a lousy ~60Mhz overclock.
My next one did 1800Mhz... and the latest one reached 2200Mhz!!
all this over a period of 1.5years.
let the FX/64 CPU grow a bit, and you'll see the overclocking capacity grow also.
exact same thing happened at the Intel side, where the first P4's (socket 423) were almost not overclock-able, the latest ones ("C" series) come close to a 50% overclock without extreme cooling.