Intel's Pentium M on the Desktop - A Viable Alternative?

Final Words

As a mobile processor, the Pentium M cannot be beat - we've actually seen why, even in this comparison today. With a highly power optimized architecture, the Pentium M continues to deliver performance that is competitive with other mobile CPUs on the market. The problem is that in the transition to the desktop world, its competitors get much more powerful, while the Pentium M is forced to live within its mobile constraints.

Think of it like this - the Pentium 4 and Athlon 64 are clearly the stronger chips of the three, as we have proved in today's review. However, in the mobile world, the Pentium 4 and Athlon 64 are often castrated or limited either by low clock speeds, single channel memory controllers or more physical constraints (e.g. you can get desktop P4 performance, but only in a 13lbs notebook). The Pentium M however, was designed from the ground up with these types of constraints in mind, and thus, excels quite well with them in place. Begin to remove the constraints and the Pentium M appears to be much less impressive compared to the Pentium 4 and Athlon 64 because the chip was designed to perform best with those constraints in place. The very low latency 2MB L2 cache is a prime example of this design mentality. A large L2 cache reduces the need for a high bandwidth memory bus, and making it low latency means that the CPU is even less dependent on such a bus.

The fact of the matter is that the Pentium M, while excellent as a mobile CPU, isn't the response from Intel that everyone is hoping for. The successor to the Pentium 4 won't be an architecture derived from the Pentium III, there's just no way around that. Intel has invested too much time and money into the optimization of applications for the Pentium 4 architecture and its execution core to throw it all away and revert to the old way of doing things.

That isn't to say that elements of the Pentium M design won't be included in Pentium 5 or whatever the next chip will be called. Even today's Pentium 4 already has a handful of key features borrowed from the Pentium M design. We saw examples of this with the launch of Prescott; the indirect branch predictor used in Prescott was originally introduced with the Pentium M processor. It would also be safe to say that a number of improvements that Intel is introducing in the next version of the Pentium M, the dual core Yonah, will eventually make their way into future Intel desktop CPUs as well.

But with a very high cost of ownership, thanks to high motherboard prices and correspondingly high CPU prices, not to mention a very limited upgrade path, the Pentium M just isn't suited for the desktop. And unless these deciding factors change significantly in the near future, it won't be for some time to come.