Dude, I'm not a seasoned overclocker. I know how it works, but have very little experience...
What do the numbers mean? Seriously I have no clue. I'm assuming that 0530 means "Made in week 30 of 2005" but what do the rest of the numbers & letters mean?
The 05** is the only thing you need to worry about on the dualies as the only availible stepping for any AMD dualie is CCBWE...and you got it right, 05 is the production year and 30 is the production week...as is normal with the AMD trend the earlier produced cores are usually the absolute best with results degrading after that...and as there is no opteron dualie produced before week30 you have the absolute best
I honestly can't tell you what the specific stepping (eg CCBWE, CABNE, CABYE) is supposed to stand for however it generally refers to a specific production line that the processor comes from. Stepping is derived from the actual machine called the stepper which is what produces the fabrication therefore one can assume that CABNE is one stepper and CABYE is another. This stepping gets confusing and varies based on a number of factors...for example, CABNE are generally considered the best however the CABYE specific week40s are far superior to the CABNE week40s