Intel to crank up Pentium 4EE bus

Intel is planning to introduce a faster front-side bus on an upcoming version of its Pentium 4 Extreme Edition chip that will...

Intel is planning to introduce a faster front-side bus on an upcoming version of its Pentium 4 Extreme Edition chip that will remove a crucial bottleneck in system performance.

The soon-to-be-released 925XE chipset is a version of the recently introduced 925X chipset with support for a 1066MHz front-side bus. Current Pentium 4 chipsets use an 800MHz front-side bus to connect the processor to the memory. This vital link plays an important role in determining the overall performance of a system.

Intel will also release a 3.46GHz Pentium 4 Extreme Edition that supports the 1066MHz front-side bus in the near future. This chip will also come with 2Mbytes of Level 3 cache, just like the rest of the Pentium 4 Extreme Edition range.

The Pentium 4 Extreme Edition chip is Intel's performance leader for desktop PCs. But that performance comes at a premium, as the chip costs more than twice as much as the most powerful Pentium 4. It is marketed almost exclusively to gamers.

In previous years, Intel has relied on ever increasing clock speeds to improve chip performance. In the last 12 months, though, thermal concerns brought on by the arrival of the 90-nanometer process generation have made it more difficult to rely on pure clock speed, so the company has turned to other methods to improve performance, such as hyperthreading and cache memory.

Dean McCarron, principal analyst with Mercury Research, said that once a processor's clock speed was four or five times faster than the speed of the front-side bus, the processor was wasting time waiting for the bus to feed it data.

With an 800MHz front-side bus on its 3.4GHz chips, Intel is coming up against that limit. McCarron said a faster bus would allow the company to increase the clock speed of its chips and take full advantage of those extra clock cycles. Intel has promised to release a 4GHz Pentium 4 chip early next year.

Other companies, most notably Intel rival AMD, have changed their designs to include an integrated memory controller. McCarron said this design removed the complexity of the memory controller from the chipset and put it directly on the processor, reducing the latency experienced by signals as they travelled from the memory to the processor.

For Intel's part, the front-side bus design gives it more flexibility as memory standards change. The industry is expected to slowly move from double data rate memory to DDR2 memory during the course of next year. McCarron said AMD would have to make a minor adjustment to its chips to take advantage of DDR2 memory, while Intel could support DDR2 memory in the chipset.

Like the rest of the industry, Intel has staked its future on multicore processor designs. McCarron said these multicore processors placed even greater demands on the front-side bus or integrated memory controller, and both Intel and AMD would need to continue to improve chip performance to keep up with those demands.

Intel has said nothing about its plans for the front-side bus architecture, but it looks as if the company will keep that design in place for the rest of this year at least.

Many analysts believe that the Pentium 4 architecture that has carried Intel for almost five years is on its last legs. They expect Intel eventually to adopt its Pentium M architecture across its products, which delivers better performance at slower clock speeds.

Tom Krazit writes for IDG News Service

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