The Athlon Thunderbird 1.33/1.3GHz utilizes the same core design as all previous Athlon "Thunderbird" processors. There are no new bells and whistles, add-ons, or accessories. It is simply the Athlon Thunderbird core running at an all-time high speed of 1.33GHz.

The heart of the Thunderbird's performance comes from its level 2 cache, which runs at the full processor speed and resides on the chip's die. This high-speed cache keeps the Athlon's core well fed with data, a task that the classic Athlon's half-speed and slower level 2 cache was unable to do as efficiently, especially as the Athlon passed the 750MHz mark. At 1GHz+ speeds, the configuration of the L2 cache is extremely important, as the processor quickly eclipses the memory and FSB bandwidths. Unfortunately, the data path from the L2 cache is only 64-bits wide as compared to 256-bits on the Pentium III, affecting L2 bandwidth.

The 256KB of full-speed on-die level 2 cache and 128KB of level 1 cache are organized in an exclusive configuration, meaning data in the L1 cache is not duplicated in the L2 cache. In contrast, Intel's Pentium III utilizes an inclusive caching scheme, so all of the data found in the L1 cache can also be found in L2. Using this exclusive method, all 384KB of cache is available for data storage.

The processor runs on a 100MHz double-pumped (200MHz equivalent) front side bus (FSB), which provides about 1.6GB/s of bandwidth or a 133MHz (266MHz equivalent) FSB, providing closer to 2.12GB/s of bandwidth. Compared to the Pentium III mated with an i815E motherboard offering 1.06GB/s of memory bandwidth, the Athlon is at a distinct advantage. However, Intel's Pentium 4 operates on a 100MHz front side bus that is quad-pumped, for a total system bandwidth of 3.2GB/s, turning the tables somewhat.

Given the overwhelming success of the Athlon, it is no wonder that there is a veritable plethora of chipsets on the market supporting the processor. First, AMD's own aged 750 chipset supports the 200MHz processors, which would include the 1.3GHz Athlon. Additionally, VIA's KT133 offers the same support, though most technologically savvy consumers will opt for one of the newer chipsets on the market that also support the 266MHz Athlon CPUs. The first of these is VIA's KT133A chipset - essentially a refresh of the KT133 with support for the new 133MHz front side bus speed.

If you are ready to move away from the long-time PC133 standard, there are also a couple of chipsets with support for DDR SDRAM running at either 100 or 133MHz, double data rate. The first comes from AMD, and is known as the 760 (which we reviewed here). Many motherboard manufacturers have moved away from the 760, in favor of a less expensive, more flexible solution from Acer Labs (ALi). The MAGiK 1 chipset, like the 760, boasts DDR support, but takes connectivity one-step forward by offering an SDR SDRAM controller as well. Benchmarks from these new boards are promising, so expect a review forthcoming!