Intel 440BX

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Intel i440BX

The Intel 440BX, also known as the i440BX, is a chipset from Intel, supporting Pentium II, Pentium III, and Celeron processors. Although the i440BX chipset is dated (mid-1998), with a "slotket" adapter Pentium III CPUs (Tualatin core) in single and dual processor configurations can be supported at speeds up to 1.4 GHz. These processors can form the basis of an inexpensive upgrade since the Celeron version has a front side bus speed of 100 MHz which matches the 440BX's officially supported 100 MHz FSB speed. Indeed, the Tualatin-based Celeron is superior in every respect to the previous generations of Pentium III. However, it cannot be run in a SMP configuration.

[edit] History and rise to fame

The older Intel P6 chipsets, the 440FX and 440LX, were innovative in their own ways but quickly became obsolete. The long-lasting 440FX was used for both the Pentium Pro and the Pentium II, but lacked SDRAM, AGP, and Ultra DMA support. The 440LX came equipped with with these features, but the technologies were in their infancy at the time, and hence were slow and occasionally unreliable. The 440BX brought second-generation AGP support and increased front-side bus speed from 66 MHz to 100 MHz; this significantly increased system bandwidth.

The 440BX became one of Intel's most popular chipsets. Enthusiasts enjoyed its overclockability, with the chipset capable of running the front-side bus at speeds ranging from 66 MHz to well over 133 MHz, in stark contrast to the 440LX's struggle to top 75 MHz. A common overclock involved the pin-40 hack, or using an Abit BH6 or Asus P2B, and setting the bus speed on a 66 MHz Covington or Mendocino-core Celeron to 100 MHz. The Mendocino-core Celeron 300A became a "sweet spot" for overclockers, with nearly 100% success rates at reaching 450 MHz on a 100 MHz FSB. Other popular overclocks included the SL2W8-stepping Deschutes-core Pentium II which could often run to 450 MHz at 100 MHz FSB, and the SL35D Katmai-core Pentium III 450 MHz which could frequently manage 600 MHz on a 133 MHz FSB.

Ironically, the 440BX offered better performance than several of its sucessors. The i810 and i820 chipsets were unable to best the 440BX at the 100 MHz FSB speed. The i820 was plagued with a requirement for high cost RDRAM to reach good performance, along with a string of reliability issues involving the memory translator hub. And, unofficially, the 440BX could often be taken to 133 MHz FSB. Many enthusiast motherboards, such as the Asus P2B and Abit BH6/BF6/BE6 series, were equipped with BIOS options to set the board to this unofficial speed. With a 133 MHz FSB, the 440BX could even match the later i815 chipset, which was designed to accommodate the final Tualatin-core Pentium III. Unfortunately, running a 440BX above 100 MHz FSB resulted in the AGP video card being forced to run on an overclocked AGP bus, as the 440BX only had "2/3" and "1/1" bus multipliers. Many video cards were tolerant of this, however.

Still, the later i815 was considered the best Pentium III chipset because it offered a better feature-set and very similar performance relative to the 440BX. Not only did the i815 support a proper "1/2" AGP multiplier for the 133 MHz FSB speed and Ultra DMA 100, but it also directly supported the impressive Tualatin.