Introduction

To celebrate the launch of the original Athlon processor in 1999, AMD released two new processors: the Athlon XP 2600+ and the Athlon XP 2400+ on August 21st. Two weeks ago we examined the flagship Athlon XP 2600+, today we'll be looking at the Athlon XP 2400+. While we focused on the Athlon XP 2600+'s performance relative to Intel's Pentium 4 2.53GHz in that review, today we'll take a closer look at why we feel the Athlon XP 2400+ represents the best value in AMD's current lineup.

Before we examine the entire Athlon XP lineup, we would like to provide a brief recap of what makes the Athlon XP 2400+ and 2600+ so special. First of all, the Athlon XP 2400+ actually runs at a clock speed of 2.0GHz. For the Athlon XP 2400+ and Athlon XP 2600+ (which actually runs at 2.13GHz) AMD adjusted its processor rating system to reflect the new features that have been added to the Pentium 4, which dramatically improves its performance. Quite simply the old rating scheme was designed for older "Willamette" Pentium 4 processors with 256K L2 cache running on a 400MHz system bus. Today's fastest "Northwood" Pentium 4 CPUs boast twice as much cache and interface with a 533MHz bus. All subsequent Athlon XP releases will be based on the new formula, while previous models will retain the original formula.

Core changes

Besides the adjustment made to the processor rating system, AMD made quite a few enhancements to the core of the Athlon XP 2400+ and XP 2600+. For instance, AMD added additional decoupling capacitors to reduce electromagnetic interference. To increase yields at clock speeds above 2GHz, an additional metal layer was added and the circuit paths within the processor were optimized. Because of these modifications, die size and transistor count have increased slightly, but power requirements remain in check.

These changes will allow the Athlon XP to scale to clock speeds well in excess of 2GHz; the previous core had problems even hitting 1.9GHz. Eventually these changes will work their way down to the other chips in the Athlon XP lineup, but for now the only way to guarantee you'll get one of these newer XP cores is to purchase an Athlon XP 2400+ or XP 2600+.