12+ will give you 12.5 or 13 (i can't remember which, been so long since i used that board)
The last BIOS i put on that (the 4A) gave you 12above, which was 13, which i used to run my Athlon 1.0 @ 1.43 (13x110)
There are newer BIOS out (iirc) but not sure whether they would give you any more multipliers
Confused