The Pentium M represents a radical departure for Intel, as it is not a low-power version of the desktop-oriented Pentium 4, but instead a heavily modified version of the Pentium III design (itself a modified form of the Pentium Pro. It is optimised for power efficiency, a vital characteristic for extending notebook computer battery life. Running with very low average power consumption and much less heat output than desktop processors, the Pentium M runs at a lower clock speed than the contemporary Pentium 4 desktop processor series, but with similar performance (e.g. a 1.6 GHz Pentium M can typically attain or exceed the performance of a 2.4 GHz Pentium 4).
Essentially, the Pentium M couples the execution core of the Pentium III with a Pentium 4 compatible bus interface, an improved instruction decoding/issuing front end, and twice as much cache: 64k primary (as compared to the PIII's 32k, the P4's 8k or the Athlon's 128k) and 1MB secondary (as compared with the 256k or 512k in the PIII, P4 and Athlon). The usually power-hungry secondary cache uses an innovative access method to avoid switching on any parts of it not actually being accessed. Other power saving methods include dynamically variable clock frequency and core voltage, allowing the Pentium M to run slowly (typically 600 MHz) when the system is idle in order to conserve energy.
The processor forms part of the Intel Centrino platform.
Intel plans to release a future generation Pentium M, codenamed "Dothan," in the first quarter of 2004.