G5 Processor upgrade for G4s?

[leekohler]

Does anyone know if Sonnet (or anyone else) will ever make a G5 processor upgrade for G4s? It seems to me that if they were, they would have done so by now. Is it a 32/64-bit issue or maybe a bus speed issue?

[robbieduncan]

This was discussed to death when the G5 was announced. The bus is a major sticking point (not just speed, it talks a whole different language between the CPU and the northbridge). Also the memory bandwidth of a G4 (which is limited by the G4 north bridge) would really slow down a G5 chip.

Basically it's probably not worth it. I'd hold out for a dual-core G4 upgrade somtime in 2006 (maybe even a dual dual-core upgrade?)

[blackfox]

I am no tech genius, but there would seem to be a basic motherboard-design incompatability I would imagine.

[leekohler]

Well-Sonnet already makes a dual processor G4 upgrade. It's pricey though-about $600 I believe. I'd buy a Mac Mini before I'd do that. I was just asking because I need to upgrade my Sawtooth desktop and didn't want to get another G4 processor if a G5 might be a possibility. Thanks-you guys answered my question.

[Lord Blackadder]

This was discussed to death when the G5 was announced. The bus is a major sticking point (not just speed, it talks a whole different language between the CPU and the northbridge). Also the memory bandwidth of a G4 (which is limited by the G4 north bridge) would really slow down a G5 chip.

Basically it's probably not worth it. I'd hold out for a dual-core G4 upgrade somtime in 2006 (maybe even a dual dual-core upgrade?)

Too bad I wasn't around, I've wondered the same thing myself. I'll have to go search for the thread...

To the original poster:

Beyond technical issues that I don' understand, I think a G5 upgrade is unlikely because the G4 is still a living design offering competitive performance. The G5 doesn't offer enough inherent advantage in the chip alone to make useful on a G4 motherboard, just higher clock really. can you say strangled by the bus?

What you MAY see at some point (besides higher and higher clocked G4s) are dual-core or twin dual-core G4(2x G4s with dual cores - a tongue twister) upgrade solutions. And honestly, those will be overkill for the Powermac G4's architecture. Its' like putting a 500MHz G3 in a Powermac 6100: you can buy the kit, but you're really wasting the G3 becuse the mobo architecture is too old.

[Sun Baked]

You might as we bite the bullet and wire an IBM PPC970 Blade into a PCI slot, much easier.

The G5 requires both the CPU and the Memory controller, along with a small processor or chip -- just to initialize. You almost have a complete computer (without i/o) at that point.

And you can't plug that into a 60x FSB.

It would end up being a co-processor card, or something with an HT to 60x bridge chip.

Almost like buying a z06 vette and updating the computer to limit in it Pontiac Grand Am performance.