Ok, I see several of you have memory timing / OC'ing issues. This was an answer to KTE's post in the abit support section. It may (hopefully) clear up some issues you are seeing:
Most likely the reason you can't OC your memory is the tRFC timing. That timing on this board is measured in ns and are selectable individually for all four DIMMs. By default, the empty slots are set to 75ns. Unfortunately, for whatever reason, it'll change one populated slot to the setting it should be at (either 105ns or 127.5ns, depending on your memory) but it treats all three other DIMMs as empty with respect to that timing. Anyway, long story short, change the DIMMs that you have memory in to 105ns and try again. You can probably clock your memory higher at that point. If not, try changing both of them to 127.5ns.
Secondly, regarding your multipliers, are you all disabling Cool n' Quiet? If not, the option will not be present. You have to disable CnQ to be able to change your multiplier.