With such impressive specifications, it's no wonder that AMD is anxious to get their new Athlon out the door. Full production is taking place in Austin, Texas at Fab 25, where the Thunderbirds are being manufactured on a .18-micron process with aluminum interconnects and also in Dresden, Germany's Fab 30, where AMD has implemented their High Performance Logic Process (HiPerMOS). Although the Fab 30 processors are manufactured using copper interconnects, AMD has assured us that the overclocking potential will be no different than current aluminum-based CPU's. We'd like to test this theory when the T-birds become more widely available, since the conductive properties of copper would theoretically allow higher frequencies without compromised signal clarity.

At 120 square millimeters, the Thunderbird is about 15% larger than the "classic" K75. Even though both cores are based on a .18-micron process, it is important to remember that the 512KB cache that used to reside on the PCB of the Athlon has been reduced to 256KB, sped up to run synchronously with the core, and moved on the CPU die. This move has increased the transistor count from 22 to 37 million - that's 15 million transistors worth of L2 cache! Because of this dramatic increase in complexity, the Thunderbird core requires a little more voltage than the K75. Processors below 850MHz will require 1.7v (as opposed to 1.65 on the K75), and 900-1000MHz CPU's will be set to run at 1.75v.

Those still concerned about power supply compatibility should know that the Thunderbird consumes around 50W, roughly the same as the K75, but about twice as much as Intel's Coppermine. We didn't experience any power-related stability issues, but before buying a set of 10,000RPM SCSI-3 hard drives, make sure that power supply is at least 250W.