> The Pentium M didn't just outperform the Pentium 4M mobile chip, it also benchmarked within a few percent of the desktop Pentium 4, while consuming less power

> The Pentium M didn't just outperform the Pentium 4M mobile chip, it also benchmarked within a few percent of the desktop Pentium 4, while consuming less power and generating less heat. After a brief diversion with the Pentium D Intel essentially gave up on the Pentium 4 in favour of a multi-core development of the Pentium M, which was sold as the Core architecture. I have a personal story: the application I worked on at that time needed some complicated calculations and decisions during them -- and to complete every run took a significant time, measured in minutes, or even hours, and there was a lot to calculate. But once somebody ran the application on a Pentium M notebook, nobody could believe at first: on the notebook it run faster than on the Pentiums 4 desktops in the office, even if the notebook had lower clock than the Pentiums 4 desktops! The reasons are many, if I remember what I've understood then correctly, the Pentium 4 design was never meant to target (at least not much) the clock speeds at which it was eventually sold. Apparently there were marketing people in Intel who influenced the development of the new processors, who managed to press the engineers to target always "more GHz" -- that was simple and easiest to sell, having more GHz than competition. So apparently the Pentium 4 design was made to conceptually enable up to 10 GHz clock speeds! Today it sounds science fiction, but before that time the clock speed did rise a lot for quite a years nicely. Also apparently, some engineers warned the marketing that maybe it's not going to be easy to reach 10 GHz. "You just design the CPU, let others design the thermal and other solutions." Of course, everything but the CPU conceptual design wasn't successful: it's not just cooling the CPU off that's the problem, although that is a problem enough. There are some specific dependencies that simply don't go linearly. So in practice Pentiums 4 have been sold with the lower clock that they were designed for, most of the customers didn't notice much. So what were the Pentium M advantages? That was a processor developed by another team (not even in the USA but in Israel), and with the specific goal of doing more in less clock counts. It worked marvelously for the real life demands, like the calculations present in our application. Compared to the Pentium 4, the M also had more CPU cache, obviously enough for our application to shine. For our application Pentium M was not "within a few percent" it was really much better than Pentium 4.