Mac Musings

Intel Switching from Horsepower to MPG

Daniel Knight - 2005.08.24

During the history of personal computing, CPU speed has been the established predictor of computing power. Realizing that, Intel adopted an architecture for the Pentium 4 that was easier to drive to high clock speeds, but at the same time less efficient than the Pentium III per cycle.

If we use automobiles for our analogy, the Pentium 4 engine has a higher RPM than a Pentium III of similar horsepower.

Intel took what I call a marketing driven approach. "People want power, and higher numbers are easier to sell than higher efficiency." Alas for Intel, the rest of the market stressed better design instead of CPU speed, and then the Pentium 4 got mired in the 3.x GHz range.

The Old Efficiency

This was an anomaly in the history of CPU design, where newer CPUs have almost always had more features and better efficiency than the ones that preceded them. Old timers will recall the jump from the 8088 to the 80286 and from the 80386 to the '486 as times when Intel greatly improved computing power per MHz of clock speed.

On the Mac, the similar transitions were from the Motorola 68000 to the 68020, from the 68030 to the 68040, and from the PowerPC 60x to the G3.

In terms of efficiency, Intel and Motorola offered pretty similar performance with the same generation of CPU at the same clock speed - until the G3 shipped. That was a big leap forward in CPU design, much more than Intel's jump from 486 to Pentium, and a lot of us recall the ads that poked fun at the hot, less efficient Pentium when G3s first came to market.

While IBM and Motorola have been building more efficient PowerPC CPUs and AMD has been making more efficient x86 CPUs, Intel's focus remained on CPU speed - until now.

The New Efficiency

The new name of the game is efficiency - the miles-per-gallon rating in our automotive analogy. Intel's new CPUs are closer to the design of the more efficient Pentium III than the higher CPU speed Pentium 4.

In fact, Intel now wants to push a new measure of efficiency: processing horsepower per Watt. That's not a new number in this industry, but until now the battles have been waged over CPU clock speed and overall CPU performance.

Computing power per Watt shows how the focus is shifting to portable devices, where longer battery life is a big concern. Instead of going head-to-head with AMD's generally more efficient (processing power per GHz) designs, Intel is declaring processing power per Watt as the new measure of things.

Time will tell whether the shift works, but this is the horse Apple has attached its cart to.

Knowing Intel's clout and seeing how notebook computers now outsell desktop computers, Intel's new measure of efficiency could become a key selling point in the portable market - and eventually the low-end desktop market as well.

Where the new measure won't redefine the market is the high end - power users (graphic artists, Photoshop users, video editors, and networked servers) need raw power more than efficiency. That's part of the reason Apple's G3, G4, and G5 lines have done so well. It's also part of the reason AMD has a higher market share at the top end than at the bottom end.

This isn't to say that Intel's new designs won't also offer more processing power per GHz of CPU speed, only that the measure among power users will remain total computing power, not energy efficiency.

For the rest of us, the emphasis is switching from horsepower and top speed (like the pony cars and muscle cars of the 1960s) to efficiency (like the tinier cars of the 1970s and today's hybrid designs). We'll want to know cruising range - how many miles between tanking up or how many hours before you need to recharge the battery - more than raw  power.

This should result in smaller, lighter, less costly laptops at the low end with comparable battery life to today's laptops - and models with longer battery life that are closer in size, weight, and cost to today's notebooks.

It will be interesting to see what Apple has in mind for Intel-based iBooks and PowerBooks.