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Prelim PowerPC G5 hits 2.4GHz

Well, two of 'em managed it

Motorola has released the latest update to its PowerPC 8500 - aka G5 - processor that ups AltiVec performance and delivers consistent 1GHz and up clock speeds, one of our Apple sources tells us.

Indeed, the source claims, two of the chips in the sample set of CPUs sent to the Mac maker, clocked at 2.4GHz. Most, however, ran at 1GHz, 1.2GHz or 1.4GHz, and some - a "considerable number", says our Deep Throat - operate at 1.6GHz.

Even if some chips run at 2.4GHz, it's clear that the yields of such parts is very small indeed. So don't expect Apple to offer a 2GHz Power Mac G5 any time soon - it's more likely to be rather more conservative about the speed it can deliver. Still, 1.2GHz or 1.4GHz will be very welcome to many Mac users wondering whether we'll see anything higher than 867MHz.

The 8500 update is revision 0.6, and is said to fix the cache coherency bug we reported a little while back. There still appears to be an issue with the G5's AltiVec performance, so while that has been improved with this revision, it's still only around 85 per cent of the third-generation G4-class processor, the PPC 7460 aka Apollo.

Our source suggests that revision 0.6 also features "minor changes with... the positioning of the L1 and L2 cache on the die". We're a little concerned by this. We'd have assumed that would have been to significant a change to be made in a point revision since the positioning of one, large collection of transistors will affect the positioning of all the others. Then again, in these days of computerised chip design tools, perhaps it's not that big a deal. We welcome comments from readers engaged in chip development work to give us some insight into this one.

Looking ahead, G5 revision 0.7 is expected to arrive sometime during the next few weeks. It promises to improve AltiVec performance further.

Its upcoming availability hasn't stopped Apple shipping 1000 prototype G5s to "key developers", according to our source, under plain wrappers - beige ATX cases, in this instance. "There are 500 machines out there, and with this revision the aim is to bring it up to 1500," boasts our source, noting this will be done through a mix of complete systems and upgrade logic boards.

Someone, somewhere out there in developer land must have seen one of these beasts. If you have, feel free to drop us a line about it. ®

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