Introduction
MSI 'Granite Bay' E7205 GNB MAX Motherboard
It seems as if DDR chipsets are all the rage for the Pentium 4. Granted, they may not be quite as fast as PC1066 / RIMM4200 RAMBUS, but DDR's widespread availability and compatibility makes it perfect candidate for use in home desktop systems. Indeed, the limitations imposed by the difficulty in producing large modules of super-fast RAMBUS have meant that those professionals looking to use vast amounts of system RAM (1GB+) have had to turn towards DDR to fulfill their requirements.
The inherent trouble with DDR is its inability to meet the P4's (or Xeon's) bandwidth requirement. Even using DDR400 memory leaves one with a potential 3.2GB/s at 133FSB, whereas the quad-pumped processors can utilise as much as 4.26GB/s. The question was, therefore, how could you continue to use widely available DDR and still meet, or get close to, the processors' bandwidth requirement ?.
The answer, seemingly, was to use DDR in 2 channels, i.e potentially doubling its bandwidth by routing 2 modules in the place of 1, much in the way that PC1066 RAMBUS works. The difficulty would be in designing a Northbridge that could work seamlessly with 2 sets of signals. Intel appear to be first off the block with a chipset, code-named 'Granite Bay', that appears to be able to deliver for the P4. A similar chipset, going by the internal name of Placer, seems fit for the more server-orientated Xeon market.
So, DDR that can be used in pairs, can be run with up to 4GB in place, which should perform better than any current DDR chipset, and one that can be adapted to the desktop market. Sounds like a win-win situation. Let's see just how good it is.
