Pentium III And Memory Bandwidth

Lot's of us were surprised to see Pentium 4's good results with RDRAM, remembering the sad results Pentium III had produced with the RDRAM-chipsets i820 and i840. The below graphs are taken out of the article about Intel's i815 chipset from June 2000 . They show how much a 1 GHz Pentium III suffers from the RDRAM-platforms i820 and i840.

After all i840 offers the same memory bandwidth as Pentium 4's i850 chipset, but Pentium III on i840 was not even able to outperform the good old BX-chipset. Remembering the somewhat sobering performance gains scored by Athlon DDR-systems over PC133-systems should already give you a taste for what you can expect from Pentium III plus DDR compared to Pentium III on i815 with PC133 memory. It also gives us an explanation. Pentium III is not designed for high data bandwidth. AMD's Athlon is already taking very little advantage of the higher memory bandwidth offered by DDR-memory platforms. Pentium III is actually even worse, explaining the bad results of Pentium III on RDRAM-platforms with i820 or i840 chipset. Keeping that in mind might get you prepared enough for our findings with VIA's new Apollo Pro266 Pentium III-chipset with DDR-support.