Extremely weird multiplier problem with barton 3000+

system spec:
AMD Barton XP 3000+(@2345Mhz) 1.85v 13x180
(stock is 13x166)
SI-97 & YS-Tech HSF
NF7-S (rev.2) (current bios: mantaray xt d26 cpc-off)
2 SATAs (240GB)
1.5 gig PC3200 value RAM (DC)
PNY 6600GT + VF700 (@569/1125)

my problem is this:
i can only use odd number multipliers. 13 is stock, 11 works, and 9 works. My CPU works fine at any of these multipliers.
If i want to use any multiplier in between, i can set it in my bios, but when my PC posts, it reverts to the nearest lower odd number multiplier. e.g. if i set my multiplier as 12, save, reboot, comes out at 11. If i go back into the bios it still says 12, but really is running at 11. WTF?
I have tried with original Abit bioses, and the same thing happens.
I have asked this question on many forums, and no one seems to know the answer (no one ever heard of it before).
Surely someone somewhere knows what is going on.