i820 and the NEW! Memory Translator Hub (MTH)
Intel has obviously recognized that the price of RDRAM was going to be high, thus they designed and released an add-on chip, the 82805 Memory Translator Hub (MTH), which, when implemented on the motherboard, allows the use of PC100 SDRAM. No, that isn't a typo! The i820 outfitted with the MTH will allow the use of PC100 SDRAM running the memory bus at 100MHz while the FSB runs at the higher 133MHz speed.
The MTH chip sits between the i820's Memory Controller Hub (MCH) and the RDRAM memory slots. (Please refer to our
Because the MTH shares the same pathway as the RDRAM memory slots, it is possible for motherboard manufacturers to design i820 platforms that support both RDRAM and SDRAM. Supporting both memory types would require more real estate on the motherboard given the extra space required for the RDRAM RIMM slots, MTH chip and SDRAM DIMM slots. On motherboards that support both memory types the user will have to make a choice between RDRAM and SDRAM because mixing the memory types isn't an option.