I am torn between two laptops. One has a Desktop P4 CPU @ 2.8 Ghz/533 Mhz FSB, the other has a Centrino Banias (AKA Pentium M) CPU @ 1.4 Ghz/400 Mhz FSB.

I know that the Centrino won't be as fast as the desktop cpu. Does anyone know how a Centrino CPU compares to a P4 *Desktop* CPU (NOT P4-M) running at the same frequency? (ie.: Centrino 1.4 VS Desktop P4 1.4).

Is it faster? slower? the same??

If you want speed stick with a desktop. Laptops are all about battery life. That is where the Centrino shines. The laptop with the desktop chip is going to eat batteries. Centrino frequency is variable according to the task at hand.

Although you didn't directly answer my question, I thank you anyway ;)

Battery life isn't terribly important to me, as I would be using it at my desk most of the time. But there are occasions where I think it would be useful.

The battery on this notebook lasts about 2.5 - 3 hours with a 2.8 GHz P4 desktop chip (I know someone who has a 2.66 on this laptop and gets battery times of 3 hours, which includes watching a DVD half of the time)

At peak speed, how does the Centrino chip compare to a desktop chip running at the same frequency?

1.6g pentium-m = 2.5g p4

The pentium-m makes the p4 look worse than a celeron

its too late to post a link........

johnoh, are you saying that a Centrino 1.6 is equal to P4 2.5 *desktop* CPU, or P4 2.5 Mobile CPU? (big difference, obviously ;)

Yep, the Pentium M is much faster and even though the clock is lower, its high IPC (instructions per cycle) rate allows it to do a lot more work in only a few clock cycles and you also get more battery life due to the CPU step down feature OntheHill mentioned.

Since you will be using it @ your desk for the most part, don't waste your money on the Pentium M.

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Hmmm...interesting. Although I *still* don't have an answer to my initial question...

Your question has been answered in between all the posts above, it just was not very obvious.

OK, first there was the Pentium 4 (desktop)from which came the following mobile CPU's:

0. The Mobile Pentium 4 (High performance & HyperThreading)
1. The Pentium 4-M (Optimiized)
2. The Mobile Celeron (el cheapo).

Then came the centrino (ground up) technology CPU's: This simply means rather than being just optimized for laptops, they are engineered specifically for laptops.

0. Pentium M
1. Celeron M

Now back to your puzzle, how a Centrino CPU compares to a P4 *Desktop* CPU (NOT P4-M) running at the same frequency?

(ie.: Pentium M 1.4Ghz...cough "centrino" VS Mobile Pentium 4 1.4Ghz..."desktop").

While the Pentium 4 has 512 L2 On-die Cache, the Pentium M has twice as much (1,024k L2 On-die Cache) and from these numbers you can guestimate for instance a 1.4GHz Pentium M to be equivalent to somewhere in between a 2.0GHz and a 2.6GHz Pentium 4.

Overall what this means is that Pentium M processor (Intel 855 chipset) outperforms the Pentium 4 processor GHz for GHz and your Pentium M 1.4Ghz...cough "centrino" clearly leaves the Mobile Pentium 4 1.4Ghz..."desktop" in the dust.

PS. This is ignoring that Pentium M processor uses 25 watts at full maximum compared to Pentium 4 3.4GHz HT's 100W.

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"Was your question answered?"

Pretty much! When you say Mobile Pentium 4 1.4Ghz..."desktop", you are referring to the desktop CPU, correct?

Yes indeed.

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Thanks for all the info!

Is that true that when using mobile CPU our laptop less noisy compared to desktop CPU(maybe related with the processor's fan)?

Yes, desktop CPU-based notebooks are definately louder than mobile CPU's. This is primarily due to the requirement for a faster, larger fan.

Thanks buddy ;).

Terrific discussion and excellent answers. How BAD is a celeron compared to the cpu's in your discussion.