Pentium M: Taking Back The Desktop?
It's not exactly news that the Pentium M's architecture is capable of very high performance. Indeed, ever since crossing the 2 GHz threshold, it has often only been a step behind the Pentium 4 models, even without such enhancements as the SSE 3 instruction set and Hyper-Threading. It is usually the slower system memory, notebook-grade graphics chips and slow-spinning hard drives that prevent notebooks from reaching performance similar to that of desktop systems. As far as sheer computing power is concerned, the Pentium M has always been known to be a mighty workhorse.
Interestingly, the technology that the "Pentium M" brand is based on is anything but new. If we were to retrace Intel's path in creating today's Pentium M "Dothan" (2 MB L2 cache, 90 nm process), it would first lead us past the "Banias" (1 MB, 130 nm) and end up at the tried and true Pentium III core known as the "Tualatin" (512 kB, 130 nm).
Of course, much work has been done on the core and the silicon it uses since then. In addition to a better prefetch unit, which was needed by the increased cache size, today's processors support the SSE 2 instruction set. They also come equipped with several mechanisms to reduce their power consumption. Obviously, the latter set of improvements is the most important for the Pentium M as a mobile processor designed for use in notebooks. Without these changes, the Pentium M could never have become the integral part of Intel's important the Centrino platform.
This brings us to the real strength of the Pentium M architecture, namely its incredible energy efficiency. While a current Pentium 4 can easily put out 30 to 40 watts of heat even when sitting idle - with the specification allowing a maximum of 115 watts - the Pentium M is downright frugal, with its maximum thermal design power of 27 Watts.
This low amount of heat can be dissipated by very simple means, which is definitely not the case with the current Pentium 4. This has led a few mainboard manufacturers to sense a niche in the market that needed filling.
Many users today would actually prefer a quiet and less power-hungry system over one that offers maximum performance at the cost of heat and noise. And in the end, the lower heat output also benefits the enthusiast crowd. After all, a cooler-running processor no longer requires very expensive cooling solutions, such as heat pipes, water cooling or loud, high-RPM fans. You can also dispense with tower cases designed for extreme cooling efficiency, and insulation mats to dampen the sound volume of noisy fans. As our thermal dissipation loss measurements show, this even holds true for scenarios in which the Pentium M is heavily overclocked.
Last but not least, there are also financial and environmental aspects to consider. Again, the Pentium M gets high marks in these categories. While it's true that a Pentium M tends to be a little more expensive than a comparable Pentium 4, its lower energy requirements will quickly amortize the higher initial cost, especially if the system is left constantly running. Don't forget: higher thermal dissipation loss means higher power draw, which in turn will affect your electricity bill!