There's been much controversy over Austin's (excellent) Tbred-B guide (from LowYat.net) which thoroughly describes the origin of every series of alphabetic, and numerals in all three lines of code:
"Based on many hands on observations, the 8th and 9th marks (these should be numbers, as shown below) in the second line of the sticker describes the initial speed the processor was designed for (RFBEXR2280073). If the initial model number is higher than the number you have, it means that your processor has been downgraded."
I presume much of the research done for this excellent guide, was extrapolated from information his contact at AMD's Singapore Fab provided. After reading this guide myself, I found every premise empirically verifiable. I've personally examined over 103 JIUHB 1700 TBred-B DLT3C, and 55 DUT3C's (of same). And found 100% of these "lower speed" CPU's were capable of 2100MHz - 2200MHz at default Vcore.
For this reason, I feel the guide's predictions are astute. In fact I surmise the author of bloodys.com has written his Athlon XP/Thunderbird Processor Identifier based upon Austin's theories. You can demo the program HERE
Most likely after a barrage of criticism Austin amended his guide to include the following:
"These 2 digits are the laser marker ID and used for chip tracing according to a friend who works in AMD Singapore Fabs. But we don’t quite understand the actual meaning of “chip tracing” as from what we know, the earlier production of Athlon like Thunderbird, Palomino do not have these extra 2 digits...
Maybe those CPU with one particular code for example 24 was originally designated to be made for 2400+ model.
But due to failure of achieving that speed, it will be remarked to lower model. So whether that CPU can hit 2400+ or not with default voltage doesn't help...because it has a great chance that won't run at that speed with default voltage at all..
We should treat these 2 digits as for reference only, because not 100% of the 28 chips can run at 2800+ !!
Bear in mind that the maturity and purity of wafer also affect a lot in performance. Coding will be the 2nd consideration after confirming which core is better by your eyes... o your 6th sense..
Anyway to be safe, you should pick one Thoroughbred with 25, 26, 27 code instead of 24 and 28 because we have no idea which is really the best one. Judging by our experiences after reviewing more than 50pcs Thoroughbred B 1700+ with different batch and production timeframe, code 25, 26, and 27 have less “disappointment”."
It could be the case there's semantic obscurities in the translation, as I happen to believe the 8th & 9th digits hold pertinent data. In fact in the photo at the bottom of this article, (the sticker from a Barton 2500) reads 25 in Code line 2, 8th & 9th places. I currently await a reply from a Barton 2500 owner with 27 in these places. I predict, it will be an excellent overclocker.