Certainly Athlon system owners have known this for some time, as DDR has been the mainstay for high performance Athlon systems. On the Intel side, there were some DDR chipsets for the Pentium III--but like RDRAM, DDR made little sense for the bandwidth-limited P3. VIA shipped the P4X266 chipset in the early autumn of 2001, but the well-publicized legal tussle with Intel kept that chipset from widespread acceptance, causing VIA to start its own motherboard business unit. SiS released its 645 chipset recently, but has had some problems ramping up production. On the other hand, the 645 is an interesting chipset due to its support of DDR333 ("PC2700") memory.
Intel's response was the Intel 845, which mated standard PC133 SDRAM to the Pentium 4. This is not unlike attaching a standard garden hose to a fire hydrant. SDRAM simply didn't have the bandwidth to adequately keep the Pentium 4 fed with data, and performance suffered. The Pentium 4's most compelling advantage over other processors is its high bandwidth capability, and mating the P4 to SDRAM utterly negates a hugely important advantage.
However, Intel dangled a carrot at the time of the 845 release--the chipset is also capable of supporting DDR memory, but the company wasn't happy with the state of DDR memory at that time. Most observers scoffed--after all, AMD had supported DDR for quite some time with no problems. But it is true that not all DDR modules are created equal. Given Intel's huge volumes, the concern on their part was real, if somewhat overblown.
So the 845 now officially supports DDR memory. In this first segment of a two part story, we'll take stock of how the Pentium 4 fares with an Intel DDR chipset, and contrast that to the RDRAM-based Intel 850 and VIA's latest spin of the P4X266, the P4X266A. In Part II, we'll look at a variety of motherboards, as well as performance with the SiS 645.