I think Psycho dropped that little nugget of wisdom on you without any explanation, and while the statement is factually correct it ain't anywhere close to the whole story.
PhIIs come in 3 flavors: 1) C2 stepping; 2) C3 stepping; and 3) EO stepping (the Thubans).
The C3s have improved voltage characteristics. C2s and C3s generally over-clock the same but the C3 will get you there with
less voltage. My understanding is that EO introduced lower-capacitance gating (requiring even
less voltage) so EOs tend to go as high (or higher) than C3s with similar/lower voltages (and 2 more cores!).
Here is the
BIOS and Kernel Developer’s Guide (BKDG) For AMD Family 10h Processors (pdf) with all the technical info you will ever want to know.
Now ... if you really want to cherry-pick an AMD processor
head on over to Xtreme Systems AMD and learn about the OPN & serial numbers.
You may determine the week of the year, day of the week and (most importantly) the
location on the wafer where the chip comes from. Chips from the center of the wafer are considered more 'cherry' and of higher quality.