ET, the question is not why would you want to use 2x and 1x, it is why do they not work? Candyman thinks that there is a possibility that LDT voltage is holding him back, and keeping him around 2.5. Other people using procs that had run as high as 2.8 stable are unable to get above 2.5 on this board for some reason, and feel that ldt volts are lacking.
Candyman is able to do 2.509 @ something like 1.6v and is having trouble getting anything higher stable (can boot above 3ghz, but nothing stable past ~ 2.509)with voltage as high as 1.85v (correct me if I am wrong Cman). That sounds like the mobo to me especially when others are stuck at the same exact speed when their proc ran almost 300 mhz faster on another mobo.
Cman has been doing as much research as possible. He is posting in 3 forums about this board that I know of, and is unable to figure out what is holding him at 2.509, and several people seem to be limited by this mobo at the exact same speed.
What might help candy, get in touch with someone who has gotten past the 2.5 wall with this board, and have them go through all the settings in the bios with you. Maybe there is 1 setting that is affecting your
oc and you don't even realize it.