KW7 -> upgraded CPU to Athlon XP 2900+ (Barton 2GHz)

I've been using my new KW7 for about 2 weeks and everything has worked
fine. The old CPU was a Athlon (Thunderbird) 900MHz. Today I
purchased a new Athlon XP 2900+ (Barton) with 400MHz FSB, OEM version
from MicroCenter.

I get the CPU unworkable or changed message. I can F1 and continue to
boot and the CPU seems slower than the old one. Or I can go into BIOS
and configure settings which doesn't help and sometimes results in
complete boot-up failure. One thing I noticed is that at boot-up the
CPU is recognized as 1000MHz, but it should be 2000 MHz (2 GHz). In
BIOS the new CPU isn't recognized as Athlon XP just Athlon and no
hertz model identification at all. CPU-ID recognizes it as the same
way although it does pick it as a Barton model.

Am I missing something in configuration? (ie. make some sort of soft
toggle in BIOS to unlock full MHz) I thought it would be recognized
and auto configure. Upgrading to BIOS 15 changed nothing.

--Festus
KW7
Athlon 900 (Thunderbird)
Ultra DDR PC 3200 (400MHz) (two 512MB sticks)
Seagate 80GB IDE (boot)
Maxtor 120 SATA
Ultra 350W PSU
Diamond Stealth S85 (ATI Radeon 9250)
MSI FX5200 AGP 8X
Pinanacle PCTV