Desktop Dothans 'will not replace Prescott'

Not good for HyperThreading

Intel's upcoming Pentium M-based desktop processor, possibly codenamed Conroe, will not support the company's HyperThreading technology, it has emerged.

And Intel's Prescott Pentium 4 line-up will survive the arrival of Conroe, an unnamed company marketing rep revealed this week.

According to, which cites said Intel staffer, the chip giant will indeed bring the Pentium M 'Dothan' core to the desktop - but not as a Prescott replacement.

The reason? Dothan's shorter pipeline is "poorly suited" to HyperThreading, which leverages under-utilised processor maths units and other trickery to fool the host operating system into thinking it's running on a two-way box.

HT remains a key part of Intel's desktop processor marketing, particularly in the consumer space, so it would be difficult for it to turn round in a couple of years and say that the technology is suddenly less relevant than it once was.

The Intel rep mentioned the possible arrival of dual-core Prescotts by the end of 2005 - presumably as Intel moves down into the 65nm domain - and noted that with HT in place, they will effectively operate as quad-core devices.

Not so Dothan-derived chips, which will be pushed at devices that need to run more quietly - and thus more coolly - than any future Prescott box is likely to.

It's not hard to foresee Intel segmenting its desktop Pentium line to target a broader range of machines, even though clearly they'll all be x86 PCs under the hood. Prescott will be pushed at performance-sensitive applications (desktop PCs, home media servers and the like) while Dothan-based Pentiums will be pitched at fanless, living room-based devices - much as VIA is currently doing today with its C3 x86 chip and Micro ATX form-factor.

Intel is increasingly keen to drive the chip sales by touting platforms rather than processors. A case in point is Centrino, which is promoted more as a usage model than as a CPU type. The chip giant is starting to do the same kind of thing in the desktop space - its entertainment PC concept, is one example - though it has yet to start branding its desktop platforms in the way it has with Centrino.

In any case, HT is arguably a broad enough brand name to take in a multi-core Pentium M-based chip. After all, like today's HT-enabled P4s, it will be able to run two threads simultaneously. There's nothing in the HT branding that specifies how that thread-level parallelism is to be achieved, only that multi-threading is there. You're simply replacing one chip with single physical core behaving like two logical cores with another chip that contains two physical cores operating as two logical cores.

A dual-core Dothan might conceivably still consume less power and dissipate less heat than a single-core Prescott running at a comparable speed. ®

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