Got the same problem.
Seems like you should be able to get the 3rd default in the Bios 12.5 *
166/33= 2000 but it just won't boot XP from cold
More stable at 12.5 * 133/33 =1600 but sometimes it still won't boot xp
until its warm.
When its been on for a while and got to 57 C + you can mostly get it to boot
even at 12.5*200/33 = 2500 which is OOS.
Runs Memtest and system stress no problem, just hangs at CTL/ALT/Del when
you hit a key. Power off button still works though.
Go Figure.
Alan