Intels CPUs (the P4s at least) have extremely deep pipelines, which are great for high clock speeds. Of course the higher the clock speed the greater the power consumption (also the extra logic for the out of order execution reordering to take advantage of/not be disadvantaged by the extremely deep piplelines adds to the power consumption as well).
The AMD CPUs have much shorter piplelines & so don't run as fast, and hence use less power. AMD have also been using different manufacturing techniques to help reduce leakage current.

Intels Pentium M CPUs on the other hand give very good performance (for Seti & office applications) & use bugger all power. However their gaming, video & general FPU performance is pretty sad.

There's more to it than that, but generally that's correct.

See, the P4 demon was set in motion several years ago, back in 1997-ish. At the time, Intel was releasing a full-fledged CPU that was designed from the ground up with performance in mind, barring power usage, then later would come out with a mobile version of the chip (like the 386SL or 486SL chips). To save on manufacturing costs, Intel decided to produce all chips on the same wafer and have all chips conserve power (hence the Pentium Classic's built-in instructions to respond to stand-by states and the like). Some engineers believed this was holding the CPU's potential back and wanted to go back to the original design of performance first. Thus, they started working on the P4 architecture.

This was still back when MHz was king, they knew that adding deeper pipelines would help increase clock speeds to ridiculous heights. As Grant said, all this power and speed, in electronics, there is always a side-effect, and it happens to be heat.

In the meantime, the entire industry did a shift and no longer cared about MHz as much as they just wanted something that was stable and worked well. Most computers were performing well for what the "average" user needed and didn't care to upgrade to the lastest/fastest/craziest speed available.

Now we are seeing a shift back to power conservation with Intel (their Yonah/Merom cores will include fixes for, as Grant stated, their poor performance with gaming & video).

AMD, on the otherhand, has always stayed with the one manufacturing style because of their, compared to Intel's, rather small pocketbook - they simply can't afford too many processor lines/productions. To better compete with The Giant, David simply developed a better weapon against Goliath's behemoth size (MHz) by increasing the IPC or Instructions Per Clock cycle. Adding an on-chip memory controller has helped AMD out considerably in performance and reducing wait states tremendously when having to fetch more information from RAM, creating an overall faster system.



And yes, Apple will be switching to Intel CPUs. I believe Apple chose Intel not because AMD couldn't keep up with Apple's demands, but because Intel is simply a bigger brand name, and I believe Apple got a first hand chance to see Intel's next-gen chips and how much cooler they run than today's current P4s, and they liked what they saw. Not to mention that Intel could undercut AMD in pricing simply because they are a bigger company, and Apple wants to keep hardware costs down (overall) while focusing on their software base, which has always been Apple's strong point.

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However their gaming, video & general FPU performance is pretty sad.

You might want to revisit that statement. Pentium M's are actually amazingly strong performers, especially in gaming.

All things being equal a 2.26Ghz Pentium M 780 will outperform ANY Pentium 4 based chip in games and can even give the best AMD chips a run for their money...

...the problem is that all things are NOT equal and the desktop chipsets available for the Pentium M's present major performance bottlenecks (533Mhz FSB, no dual channel DDR, no SLI etc).

However, Asus's CT-479 socket 478 adapter goes a long way towards rectifying that problem.

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thanks for the info guys :)

but i'll be honest, a fair bit of it goes over my head, i get the jist, but i'm not up to speed on processor architecture, design, engineering etc.
(things like what a pipe is, why does length matter, where and how does it fit in the big picture etc.)

can anyone recommend a site/page that explains the terminology etc. (unless they wanna explain it themselves?) as i wouldn't call myself a beginner, but i'm nowhere near "advanced"

many thanks

Lee

You might want to revisit that statement. Pentium M's are actually amazingly strong performers, especially in gaming.

For gaming I'll go from sad to not great. Acceptable but not great.

Pentium M review

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Grant
Darwin NT

can anyone recommend a site/page that explains the terminology etc. (unless they wanna explain it themselves?) as i wouldn't call myself a beginner, but i'm nowhere near "advanced"

AMD architecture explained
P4 architecture explained

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Grant
Darwin NT

can anyone recommend a site/page that explains the terminology etc. (unless they wanna explain it themselves?) as i wouldn't call myself a beginner, but i'm nowhere near "advanced"

I've been trying to come up with a good analogy, and haven't come up with a really good one.

In the U.S. we have 110v and 220v electric service. Heavy equipment uses 220v because doubling the voltage halves the amperage, but the power (the work done) is the same.

You can have two cars with different engines: a fast-revving four cylinder and a slower turning eight cylinder -- RPM is different, gear ratios are different, but they can both drive at the same speed.

In other words, clock speed doesn't mean much unless you are comparing otherwise identical processors. AMD processors generally do more work per clock than their Intel counterparts.

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thanks ned and grant, reading up as i type (well, just after i post)

You might want to revisit that statement. Pentium M's are actually amazingly strong performers, especially in gaming.

For gaming I'll go from sad to not great. Acceptable but not great.

Pentium M review

I will have to agree with Grant on this one again. Pentium M's have acceptable performance on games (my notebook is a Pentium M 1.8GHz), but not great.

Oh, and AnandTech is a great place for average tech people to learn more information. www.ArsTechnica.com is another good one too.

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