DDR SDRAM technologies are getting faster and faster. It wasn't long ago that we saw DDR-333 introduced, and only just recently Intel's adoption of this new standard. VIA, SiS and Ali have been using DDR-333 technology for about 5 months now.
DDR-400 is one of the new technologies that aren't being embraced as quickly as DDR-333 was. DDR-400 still has a few hurdles to overcome, such as instabilities when running more than one DIMM, and becoming an official JEDEC standard. So far DDR-333 has just made it into this light. To date we only have a handful of chipsets than can support this new memory. The SiS 648 is the top of the line P4 chipset with VIA taking up a bit behind. SiS did a remarkable job with this chipset as we were able to get two DIMM's of Samsung memory running DDR-400 on this board without any problems. VIA's KT400 is the only commercially available Athlon chipset to use DDR-400 at time of writing this review. With nVidia releasing their nForce2 chipset supporting 128bit interface @ 400Mhz memory we are soon to see how well this works and SiS have their own Athlon chipset for DDR-400, 748 - arriving before too much longer.
With DDR-400 not being officially supported by the major manufacturers it is hard to see why companies would be going even further. Very few are moving past 400Mhz memory due to DDR2 arriving very shortly on the market. So far we have seen only four companies with 400+Mhz modules, these being Corsair, XtremeDDR, Geil and OCZ.
While we have tested the Geil DDR-433 module, we haven't had any of the others; today thanks to Ramstore in Canada we have our hands on the new OCZ DDR-433 memory module.