Intel will double the amount of on-chip memory available to its Xeon MP processor, designed for use in 4-way servers, according to its new roadmap.

The enhancement will be included in a forthcoming release of Xeon MP, code named Potomac, which is expected in the second quarter of this year.

Intel had previously disclosed that the Potomac cache size would be larger than the 4MB available in the company's current 3GHz Xeon MP chips. The roadmap indicates that Potomac will have a clock speed equal to or greater than 3.5GHz and a cache size of 8MB.

While faster frequencies were once the standard way of improving processor performance, Intel has encountered difficulty moving its processor to 4GHz. In October, the company backed off on a promise to release a 4GHz version of its Pentium 4 chip, and none of the Pentium or Xeon processors on the server roadmap list frequencies higher than 3.8GHz.

Intel has also made design decisions that limit the speed with which Intel's processing cores can communicate with memory, forcing the company to boost performance by building larger and larger caches, said Kevin Krewell, editor-in-chief of the Microprocessor Report. "Because they lag in that feature, that's one of the reasons they have to build up the cache size," he said.

Also listed on the roadmap is a 3.8GHz Pentium 4 processor called the 660, which will have 1MB of on-chip memory when it ships in the first quarter of 2005. There is also a Pentium 4 670, which is expected to have 2MB of cache by the third quarter, as well as a dual-core Pentium chip called the "X40", scheduled for the same time frame.

The "x" in X40 is most likely a placeholder as Intel figures out whether to call the chip, which is code-named Smithfield, the Pentium 4 740 or Pentium 4 940, Krewell said.

Intel declined to comment on the server roadmap, which was first reported by the Inquirer. The roapmap itself can be found here [pdf].