The AMD Athlon 1.4 GHz is yet another core speed increase to the existing Thunderbird design. Its specifications are the same as previous Athlon high performance processors, featuring a .18 micron core, 128K L1 cache, 256K full-speed L2 cache, the EV6 DDR system interface and a 1.75V core voltage.

Maintaining the current core design spells good news for performance aficionados and upgraders, as the Athlon 1.4 GHz will be compatible with existing Socket A motherboard technology. This makes it a simple step for system integrators to quickly offer Athlon 1.4 GHz systems, and just as easy for current Athlon owners to upgrade their systems to the newest and fastest processor. We tested our review unit in both DDR and SDRAM motherboards and it initialized and performed flawlessly.

The 1.4 GHz speed looks to be nearing the top-end for the Athlon Thunderbird core, and experts have pegged the new Athlon Palomino core (as seen in the portable Athlon 4) to start at approximately 1.5 GHz for the desktop version. While I wouldn't bet against seeing a forthcoming 1.46 or 1.53 GHz Thunderbird, the 1.4 GHz model is definitely approaching the end of the line for this particular core.

As with all other Athlon Thunderbird processors, the new Athlon 1.4 GHz includes 128k of L1 cache and 256K of full-speed, on-die L2 cache. This makes the Athlon the desktop processor with the highest level of internal cache, surpassing both the Pentium III Coppermine (32K/256K) and the Pentium 4 (8K/256K), as well as the AMD Duron (128K/64KB). AMD has also designed their processor cache to be exclusive, thereby ensuring that both the L1 and L2 do not needlessly duplicate data. Of course Intel has their own advantages, such as a higher L2 cache bus (256-bit vs. 64-bit for AMD) and lower cache latencies.

One of the more pressing needs in the performance PC arena is for improvement in both system and memory bandwidth. The Athlon features a DDR (Double Data Rate) system bus and transfers data on both the rising and falling edges of the clock. On a basic 100 or 133 MHz system bus, this allows the Athlon to transfer data using an effective 200 or 266 MHz system bus. This is also true when using DDR memory, and give the Athlon 266 MHz DDR systems the potential of 2.1GB/s of bandwidth for both system and memory transfers.

This places the Athlon ahead of the Intel Pentium III (100/133 MHz) and new Celeron (100 MHz) processors, which rate at only 800 MB/s to 1.06 GB/s of system bandwidth. The Pentium 4 ups the ante considerably in this area, and its RDRAM architecture and quad-pumped 100 MHz system bus (400 MHz effective) translate into a whopping 3.2 GB/s of bandwidth.