Mine came with 667... but I think seeing on partsurfer an option for 533 spec'd ram.... Of course that doesn't mean much as there are allot of incorrect descriptions on partsurfer.
adniu has it right... I think that is how DDR-2 is addressed.
I wouldn't count too much in most of the reporting programs that report the various speeds of things (as some here recently found out on the GPU's on some of the latest GPU's) unless your running the latest version, and the author updates the program for new cpu's chipsets.
On most of the free, non-commerical type programs what I've run into is unless the author has that chipset , etc it doesn't get added properly, may not work right... Since there is no way for him to test, no major incentive to do so... Spend allot of time fine tuning. Of course most will add the data if they get feedback from the users... then again if they don't have the hardware to test........