The i820 is based on the same HUB architecture as the already shipping, low-end i810 chipset. Basically these two chipsets architecture's are identical except the i820 has a 4X AGP bus (without video integration), 133MHz FSB capability, and RDRAM support. We did two comprehensive reports on the i810 chipset in April 99:
These diagrams demonstrate the i820's advantage with its new architecture. Due to the MCH having direct access to the memory bus, the slow PCI bus does not limit the i820. The i820's UDMA66 support provides twice the bandwidth as the 440BX's UDMA33. However, even the fastest ATA-66 drives can only sustain ~13MB/s transfer rates.