Found this about the AMD XP Athlon on good'old wikipedia.
Specifications:
Barton (130 nm)
L1-Cache: 64 + 64 KiB (Data + Instructions)
L2-Cache: 512 KiB, fullspeed
MMX, 3DNow!, SSE
Socket A (EV6)
Front side bus: 166/200 MHz (333/400 MT/s)
VCore: 1.65 V
First release: February 10, 2003
Clockrate: 1833 - 2333 MHz (2500+ to 3200+)
166 MHz FSB: 1833 - 2333 MHz
(2500+ to 3200+)
200 MHz FSB: 2100, 2200 MHz
(3000+, 3200+)
3000+ appears to be 200 fsb, as standard.
is his cpu definately the 3000+?
could be a 2500+ or 3200+ overclocked, and you are positive its not overclocked? I would say if you reverted back to defaults and its changed the fsb, its a sign it has been OC'd.
If it has been OC'd could be ram n cpu speeds not in sync etc.