Overview

Overview

The Pentium M represented a new and radical departure for Intel, as it was not a low-power version of the desktop-oriented Pentium 4, but instead a heavily modified version of the Pentium III Tualatin design (itself based on the Pentium Pro core design). It is optimised for power efficiency, a vital characteristic for extending notebook computer battery life. Running with very low average power consumption and much lower heat output than desktop processors, the Pentium M runs at a lower clock speed than the laptop version of the Pentium 4 (The Pentium 4-Mobile, or P4-M), but with similar performance - a 1.6 GHz Pentium M can typically attain the performance of a 2.4 GHz Pentium 4-M. The Pentium M (model 740) has been tested to perform up to about 7,400 MIPS and 3.9 GFLOPS (using SSE2).

The Pentium M coupled the execution core of the Pentium III with a Pentium 4 compatible bus interface, an improved instruction decoding/issuing front end, improved branch prediction, SSE2 support, and a much larger cache. The usually power-hungry secondary cache uses an access method which switches on only the portion being accessed. The large size of the cache was in fact so that a decent-sized portion of cache would still be available to the processor even when most of the L2 cache was switched off, but its large size led to a welcome improvement in performance.

Other power saving methods include dynamically variable clock frequency and core voltage, allowing the Pentium M to throttle clock speed when the system is idle in order to conserve energy, using the SpeedStep 3 technology (which has more sleep stages than previous versions of SpeedStep). With this technology, a 1.6 GHz Pentium M can effectively throttle to clock speeds of 200 MHz, 400 MHz, 600 MHz, 800 MHz, 1000 MHz, 1200 MHz, 1400 MHz and 1600 MHz; these intermediate clock states allow the CPU to better throttle clock speed to suit conditions. The power requirements of the Pentium M varies from 5 watts when idle to 27 watts at full load. This is useful to notebook manufacturers as it allows them to include the Pentium M into smaller notebooks.

Although Intel has marketed the Pentium M exclusively as a mobile product, motherboard manufacturers such as AOpen, DFI and MSI have been shipping Pentium M compatible boards designed for enthusiast, HTPC, workstation and server applications. An adapter, the CT-479, has also been developed by ASUS to allow the use of Pentium M processors in selected ASUS motherboards designed for Socket 478 Pentium 4 processors. Shuttle Inc. offers packaged Pentium M desktops, marketed for low energy consumption and minimal cooling system noise. Pentium M processors are also of interest to embedded systems' manufacturers because the low power consumption of the Pentium M allows the design of fanless and miniaturized embedded PCs.
Intel Pentium M processor family
Original Logo New Logo Laptop
Code-named Core Date released
Original Pentium M brand logo New Pentium M brand logo Banias
Dothan (130nm)
(90nm) Mar 2003
Jun 2004
List of Intel Pentium M microprocessors