If Switching, Timing Is Everything.

Apple have shown some absolutely stellar benchmarks with the Core solo and Core Duo processors outperforming their G4 based predecessors by quite a considerable margin in most areas, heavily vectorised applications are seemingly the only exception. The story is not quite so clear with the G5 based iMac but there is a difference even there.

These benchmarks can be considered no doubt as justification for the decision to switch to x86 processors. However, in typical Apple style there is some sleight of hand, in particular as regards timing of the switch. Making the transition 6 months early is no mistake, it was absolutely critical to get those benchmarks.

By going early Apple have been able to emphasise the difference between the processors. The Core Solo and Core Duo processors are brand new designs and are manufactured in a 65nm silicon process. The PowerPC processors they are being compared to on the other hand are not brand new, in fact both have been superseded by newer products which are both faster and cooler.

The PPC iMac uses a single core G5 970FX with a 512K cache, this has been replaced by the single core 970GX, these run up to 3GHz, run cooler and have a 1MB cache. They also use the newer G5 bridge chip which fixes the latency problems the original G5 bridge had.

The PPC PowerBook and Mac mini uses a G4 7447A with a 167MHz bus and a 512K cache, it is built on a 130nm process, two generations behind the Intel chips. The latest G4 is the 7448, it runs on a slightly faster 200MHz bus and (more importantly) has a 1MB cache. This chip is built on a 90nm process which allows it also to run faster and cooler.

If Apple had waited to the middle of the year things they would have likely updated their range with the newer PPC processors and they wouldn’t be able to make such a comparison. The G4s would still lag the core duo products but not by the same margin. The current G5 isn’t getting battered like the G4, core for core there isn’t a great deal of difference between the PPC and Intel parts. The 970GX will be faster per clock then the 970FX so it might actually lead in the single threaded benchmarks. If Apple had waited until the summer there’d be a lot of people wondering why Apple was switching.

If they’d waited until later in the year it’d be even worse. Intel have new products due based on a new architecture which looks very good but by then the G4’s successor, the 8641D should be ready. The 8641D has dual cores and dual on-chip memory controllers, they should pretty much blow the existing G4s out of the water. The next gen Intel parts may still be faster overall but not by even close to the same margin. There’s also a completely new Power processor due from PA-Semi which looks like it’ll not only match the Intel laptop parts on performance but use less power doing so.

The decision to switch to Intel parts doesn’t seem to be have been taken for the reasons given. The decision appears to have been financially and strategically based rather than on any technical considerations, it was a business decision. It looks like Intel and Apple have “partnered” in some form in an arrangement which goes beyond just processors. Indeed, the announcement of the Apple-Intel-Micron (AIM 2?) flash memory alliance a while back shows just that.

It’s quite ironic that Apple switched to x86 just as Power is about to undergo something of a renaissance, there are no less than 5 new Power based processors due in the next year or so: 8641D, 1682M, the POWER6 derived P6L, a 3GHz part from AMCC and of course Cell. There’s no doubt that the G4 had got behind but that would have soon been solved, that said the G4 wasn’t exactly holding them back, Apple’s sales were growing rapidly even before the switch was announced.

The are no doubt some benefits of using an industry standard architecture but the seemingly large performance differential is due to some very clever marketing on Apple’s part. By being very clever with their timing, they have be able to get 3rd parties to compare the latest Intel chips to previous generation PowerPCs. It’s really no surprise the benchmarks are so good, the dice are loaded.

It’s not clear how long the Apple Intel deal is set to last, but the switch does allow Apple to have some interesting options ahead of them. Universal binaries can run on both x86 and Power chips and each of those families has different strengths and weaknesses. Apple could if they so wished pick and chose processors from both. There's no indication they are planning on doing this but it'd be quite an advantage given no other PC maker has even the possibility of this option.

Note: Before I get accused of slagging off Apple, I should point out I am a happy Mac user and would actually quite like one of those Intel MacBooks...