April 1998 saw Intel launch its sucessor to the LX chipset, the i440BX (which we shall refer to as just BX) chipset. The BX was brought with it a number of improvements over the LX, but overall it was not a huge jump in chipset architechture, unlike what its sucessor the i820 is.

Unlike the LX, the BX has enjoyed nearly 18 months as Intel's premier desktop chipset even outlating the Pentium II as it now supports the first generation of Pentium III (Katmai) processors.

Intel i440BX, what does it do?

The big improvement which the BX brought over the LX chipset was the addition of the 100 MHz front side bus for the Deschutes core Pentium II processors. This was the first big jump in bus speed since the introduction of the Pentium in 1993 which brought in the 66 MHz bus which reigned until April 1998. The 100 MHz bus allowed Intel to utilise lower clock multipliers for its higher speed processors whilst increasing the memory bandwidth available to the CPU and main system memory.

New PC-100 SDRAM was needed to run the 100 MHz bus memory which was demanded by Pentium II processors from 350 MHz upwards. Unlike previous changes to bus speeds which were introduced on some Socket 7 boards needed to run some Cyrix chips, the BX did not overstress the PCI bus, but instead used a divider of 1/3 to keep its speed down to 33 MHz.

The introduction of the 100 MHz bus was not just the only improvement the BX brought with it. The BX kept with it all the improvements brought in with the LX, but also added support for up to 5 PCI slots and for up to 1 Gb of main system memory to be fitted in either EDO or SDRAM. There was also support added for SODIMM memory modules and the BX could also be fitted to mobile motherboards, thus bringing the Pentium II into the mobile market. Lastly the BX brought in additional power saving modes to those already added with the LX chipset.

The BX chipet has found itself fitted to a variety of motherboards. Originally most BX chips were fitted to Slot 1 ATX motherboards, but with the introduction of Socket 370 in 1999, a number have been used on Socket 370 boards designed for the Celeron as it still includes support for the 66 MHz bus. There have also been many boards made in the micro-ATX form factor.

The BX chipset supports all Intel Pentium II processors, Pentium III chips up to 600 MHz (not 533(B) and 600(B)) and Celeron processors up to 500 MHz.

The BX is currently in production.

BX in use.