Core Changes

Improving the Thoroughbred's formula

As we mentioned earlier, the clock speed on the Athlon XP 2600+ model operates at 2.13GHz, and the Athlon XP 2400+ runs at 2.0GHz, both running on a 133MHz (effectively 266MHz) system bus. Both chips are also based on AMD's "Thoroughbred" core, which is based on AMD's brand new 0.13-micron manufacturing process. However, unlike the original Thoroughbred Athlon XP 2200+, these two chips are based on a radically different processor stepping.

If you recall back when the AXIA "Thunderbird" Athlon processors were all the rage, you probably realize the significance of this immediately: overclocking. You see, as AMD gets more experienced with a manufacturing process, they slowly implement new manufacturing improvements. This allows them to improve their yields. With the older Thoroughbred steppings, getting chips at 1.9GHz was difficult enough let alone 2GHz. Getting good yields on the 2.13GHz part would have been next to impossible. Fortunately AMD's engineers were able to implement a new stepping on Thoroughbred -- just in time for the Athlon's three-year anniversary.

In the case of the Athlon XP 2400+ and 2600+, AMD has added another layer to the Thoroughbred core, bringing the total up to nine layers. In addition, AMD has added additional decoupling capacitors to reduce electromagnetic interference (which is important when your chip is running at speeds of 2GHz and above). Finally, AMD has optimized the circuit paths within the processor.

As a result of these changes, die size has increased slightly: while the original Thoroughbred's die size was 80mm2, the XP 2600+ features an 84mm2 die. Transistor count is also increased to approximately 37.6 million. Despite the increased clock speed, typical thermal power is only 62W, while the maximum is 68.3W (versus 61.7W and 67.9W for the slower-running XP 2200+).

Now that you've got that information down, here's the new chip:

Athlon XP 2600+

Note the AIUAB stepping

The important part to look at here is the bottom line of the Athlon XP's ordering part number. In our case, it reads AIUAB0231RPAW. "AIUAB" is the stepping of our processor, with "02" designating that it was made in 2002 and "31" meaning it was made the 31st week. She's brand-spanking new baby!

Like the old AXIA chips AMD will implement this stepping on its slower Athlon XP chips, but obviously they're going to ship as many of them at 2.0GHz and 2.13GHz as possible. After all, the selling price on these chips is considerably higher than the older Athlon XP parts. Which brings us to our next point, pricing. Officially, AMD is listing the Athlon XP 2600+ at $297 when purchased in 1,000 unit quantities and the Athlon XP 2400+ is priced at $193.