Finally, the unsupported Tualatin-core Pentium III could be used with an adapter and various modifications, with varying degrees of success.

The i820 was plagued with a requirement for high cost RDRAM to reach good performance, along with a string of reliability issues involving an RDRAM-to-SDRAM memory translator hub in designs using that chipset with SDRAM.

Enthusiast motherboards, such as the Asus P3B-F 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.

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 divider for the 133 MHz FSB clock rate, AGP 4x, and Ultra DMA 100, but the later revisions also directly supported the Tualatin Pentium III; however, the i815 had a RAM limit of 512MB compared to 440BX's 1GB RAM limit.

The higher end 440GX chipset released in June 1998 that was originally intended for servers and workstations has this support.