Alastair’s Place

Software development, Cocoa, Objective-C, life. Stuff like that.

Microprocessor Myths

In the 4th August issue of MacUser (the U.K. magazine, not its U.S. cousin), I read yet again the assertion by a journalist—Kenny Hemphill—that “The truth is, it’s many years since the PowerPC has been able to compete with Intel or AMD processorsâ€?. It really annoys me to read this. Not only is it untrue, but it’s quite unfair to the very talented engineers who worked on (and continue to work on) the PowerPC processor ranges.

The press usually support this assertion with the argument that Apple changed microprocessor because the PowerPC couldn’t keep up. Sorry guys, but this one’s just plain wrong. Apple changed microprocessor because of the various architectures’ predictions of future performance per watt. It wasn’t that the PowerPC didn’t give the right bang for your buck, but that Intel showed them technology that ran cooler at the same performance level. And when they said that (at WWDC), Apple were talking about the Core family of processors, not any previous Intel designs.

What never ceases to amaze me is the poor standard of journalism that this constant assertion about PowerPC performance actually represents. Journalists are supposed to report facts, not total speculation, but whenever they come out with this one, they are ignoring the published performance figures for machines with the various processor architectures:

ProcessorClock Freq/GHzSPECint2000SPECfp2000
PowerPC G52.717062259
PowerPC G52.515872119
Pentium 43.818632091
Pentium 43.417051561
Athlon 64 FX-572.819702261
Athlon 64 FX-532.417001634
Core Duo T26002.1617961615

According to these figures (from the SPEC website), at 2.7GHz the G5 is equivalent to a 3.4GHz Pentium 4 or a 2.4GHz Athlon 64 FX-53 for integer performance, but can keep up with a 2.8GHz Athlon 64 FX-57 or significantly outperform a 3.8GHz Pentium 4 for floating point. As for the Core Duo chip used in the new Intel Macs, well has a slightly higher integer performance than the fastest G5 chip, but the G5 comfortably outperforms it at floating point.

The point is that the G5 is certainly comparable in performance terms with all but the very latest Intel and AMD chips, and in some areas, it will outperform them. The received wisdom from the popular computing press is completely wrong.

It is true that the Core 2 Duo is substantially faster. But it’s only just been released so it’s still a gross misrepresentation to point at the Core 2 Duo and claim that the PowerPC hasn’t been as fast as Intel or AMD offerings for ages.