Well last night at 2am I was finishing up the overclocking section on the Asus P4P800S-E motherboard and saw a BIOS setting for 275FSB/550MHz Memory. I was like WTF let's give this a try. (Early yesterday I got in XMS 4400)
So I used a brand new 512mb module of XMS 4400 at 2.85vDimm and "plugged and chugged"! Sure enough the system posted and I was running 550MHz DDR on a single channel board! With the Intel 848 chipset!
Holy crap! Pretty impressive for a board geared at OEM's and budget buyers!