first if it shows 667mhz, then it's running at default of 1333mhz because DDR is doubled.
second, how are you trying to set the ram speed? the AMD chips only officially support 1333, but most MB's can help that go faster. I have 1866 and the same board and it's fine.
What you need to do is go into the bios (and this is off the top of my head, so I may be wrong but look around) and going the advanced options, AI tweaker settings or something and turn that to manual I think from AUTO or DOCP is what you want to find anyways. DOCP is the same as XMP on Intels and it basically asks the RAM for it's speed and stats and then from there you should be able to in the drop down box below the DOCP option is select the speed and you should see...