What AM3 compatible mATX motherboards can unlock cores? I just heard something about some motherboards not being able to do that...
Biostar mobos can. But remember that this is not a sound method. And it's hit/miss, most likely most can unlock, but then again, not everyone's made of horse shoes.
Gigabyte GA-MA785GMT-UD2H , mATX, AM3, what more could you want? Ok, 790FX... but oh well... As for the cores:
Gigabyte AM3 and Asus AM3 motherboards can with their latest BIOS afaik. The 785Gs certainly can. Check manufacturer websites and the BIOS changelogs. The Gigabyte and Asus boards work great by the way I've been making quad cores from 720BEs on both