Celeron M vs Pentium M query

I have a 1.5GHz Celeron M (1Mb cache). I am considering an upgrade/sidegrade/downgrade (hence the question) to an ebaytastic Pentium M.

Why? Power saving - no point running the whole CPU if I can get a cheap P-M that shuts down when I'm just browsing and listening to music. Which will keep the fan off more, save electricity, and all that.

So here's the question.

Celeron M/1Mb/1500MHz vs Pentium M/2Mb/1400MHz

Extra cache, but slower clock. Faster or slower? ("Depends on the applications..?")

Of course it makes no difference when I'm doing the dull stuff, but will it help or hinder in games? Worth trying to get a 1.6GHz+ one for twice the price of the 1400?

Or is it all just a complete waste of time....

Pentium M will be faster..... I imagine

PM is faster- is this a laptop or desktop upgrade and what clock speed you looking for / price?

Laptop upgrade, small amounts of cash! If the 1400MHz/2Mb is gonna be faster than my 1500 Celeron then that'll do me.

OK, the P-M will DEFINITELY get you better power management, and the extra MB of L2 should more than compensate for the 100MHz clock drop. What laptop is it going into, please?

Tosh Tecra A4

OK, according to Tosh, that's based on a 915PM chipset. That should support a P-M with up to a 533MHz FSB. Looks like there's a lot better options for your machine, as per Intel.

Indeed, but the 1.4GHz ones are cheap, and anything faster is horribly expensive. If you have a link to a reasonably priced 533 FSB chip, go for it! But bear in mind this whole laptop cost not much more than £500 (its one of the "oddball" A4s, with 128Mb X300 and no spangly new PCCard slot).

It basically does me well, I was just thinking that when I'm doing very little it'd be nice to have the cpu "spin down" and save the fan and a bit of energy :)

But if you can find me a nice 1733 or 1866 for a decent price..cool!

The Pentium M is by far the better bet, the Celeron Ms lack a load of power management features that are on Pentium M and it also lacks the bigger cache that is very beneficial on Intel's architecture as it still features a traditional FSB.

Well, I chucked a P-M 1600/400/2Mb in this evening...all seems okay now, unfortunately the fan still spins on "low" most of the time :( This is with the cpu at 600 MHz, apparently its at 46 degrees C. Not sure if thats a bit high or not? It ran through Super PI to 32 million places so I guess I can't have botched the install too badly...

use nhc notebook hardware control and drop the voltage down as low as you can on its lowest multiplier and test each step dropped my temps a fair whack