Before the Athlon XPs with Barton cores were even launched, we started getting a deluge of e-mails from readers wanting to know how effective the coolers that ship with boxed Athlon XPs actually are. And yet another outpouring of e-mail basically read: "I've got an Athlon XP 2400+ and want to upgrade to an Athlon XP 2700+. Do I need a new, more powerful cooler?"

Let's first take a look at the maximum thermal-power readings of high-end Athlon XPs with Thoroughbred A, B and Barton cores (source: AMD Data Sheets Processor Model 8 and Model 10):

The Athlon XP 3000+ with a Barton core has the highest maximum thermal power: 74.3 watts. But since its die is 20 percent larger than high-end models with Thoroughbred B cores, such as those you'll find in the Athlon XP 2600+ and 2700+, its maximum specific thermal power is almost eight watts (or some ten percent) less at 73.56 watts/cm².