What chipset are they running? I'm guessing it's a VIA chipset, and if thats the case, dont expect to OC any higher then 2.0-2.2Ghz. They are horrible overclocking boards, and the chipsets dont even have SATA locks, so if you use a SATA drive it will give you errors at even the slightest overclock.
Their BIOS also has very limited OC'ing functions, and you can usually only change the FSB and a few other settings - no voltage controls.