The Right Memory Type For Pentium 4
Pentium 4 likes high bandwidth or it can at least take advantage of it, due to the high bandwidth of its processor bus. The 100 MHz clocked and quad-pumped P4-bus has a bandwidth of 3.2 GB/s, which is just as high as the dual-channel RDRAM memory configuration of the i850 chipset. The 1 GB/s of i845 with PC133 SDRAM are significantly less than what Pentium 4 would be able to compute, which is why even the very low latency of PC133 won't be able to make up for it.
Unfortunately it has become common belief that Pentium 4 was 'designed for RDRAM'. This is of course nonsense. Intel would be rather crazy if it would indeed design its processors for one particular memory. RDRAM memory would be a extremely bad choice, since its acceptance in the market still remains very low, partly due to Rambus unethical actions of listening to ideas in JEDEC-conferences and then patenting them as their own inventions and milking JEDEC members with demands for license fees.
Pentium 4 has been designed for high memory bandwidth. This can also be provided by DDR-SDRAM and especially by dual-channel DDR solutions as just realized by NVIDIA in form of the nForce chipset. We will see that Pentium 4 suffers from the low performance of PC133 SDRAM. However, the story might well be very different with DDR-SDRAM. Industry sources are already talking of the superior performance of i845/DDR solutions in some applications, while others claim that VIA's upcoming P4X Pentium 4 DDR-chipset will outperform i845/DDR as well as i850. I won't believe that Pentium 4 'requires' RDRAM until I have seen it with my own eyes. So far Intel is trying its hardest to ensure that RDRAM does indeed remain the best performing memory type for Pentium 4. However, sooner or later someone will run Pentium 4 with something that is faster than PC133 memory. We will see if RDRAM will remain the best P4-memory then.
Antichrist Rambus Reason For I845/DDR Delay?
The i845 chips that are available to motherboard makers right now do not just support PC133 SDRAM. They are already coming with full-blown DDR-SDRAM support, but Intel does not want any i845/DDR platforms to ship before January 2002. Several people have speculated that this is due to Intel's deal with Rambus. However, as appealing as those speculations may be, I doubt that Intel will intentionally jeopardize Pentium 4 sales for a petty agreement with naughty Rambus, the memory Antichrist. If Pentium 4 plus RDRAM doesn't sell well, then Pentium 4 plus PC133 will sell even worse. The latter combination may be less expensive, but its performance is dangerously close to what current or near-future Pentium III platforms are able to offer. Pentium 4 needs DDR-SDRAM support and Intel cannot be that much on drugs that is wouldn't realize it.