DUAL G4 Upgrade for Gossamer and Yosemite Macs???

[Quadraman]

http://macspeedzone.com/archive/01/upg_revw/xlr8/mpe_dual_500.shtml

Has anyone used one of these?

 

[coius]

from what I heard, those things caused a LOT of data corruption, mainly as the North-Bridge of the G3 was specifically made to only support 1 Processor per north-bridge from my understanding. Hence the reason in the gap between Dual Processors (dual 604x, skipped G3, then did Dual G4)

I don't think IBM wanted to try to work in Dual Processors since the PowerPC 750 (a relatively cheap design) would interfere with it's more Powerful CPUs that they were marketing in the server/mainframe categories.

To be honest, Dual G4's wouldn't make a difference, since in OS X it was practically unusable (OS X would only run one CPU, an inherent design of the north-bridge for the G3).

I wouldn't even pay the money for the novelty. I would just with either a fast G4, or a REALLY fast G3 on either a Beige, or a B&W G3 or Yikes!

Also, the tests they showed weren't that impressive...

 

[Quadraman]

from what I heard, those things caused a LOT of data corruption, mainly as the North-Bridge of the G3 was specifically made to only support 1 Processor per north-bridge from my understanding. Hence the reason in the gap between Dual Processors (dual 604x, skipped G3, then did Dual G4)
I don't think IBM wanted to try to work in Dual Processors since the PowerPC 750 (a relatively cheap design) would interfere with it's more Powerful CPUs that they were marketing in the server/mainframe categories.

To be honest, Dual G4's wouldn't make a difference, since in OS X it was practically unusable (OS X would only run one CPU, an inherent design of the north-bridge for the G3).

I wouldn't even pay the money for the novelty. I would just with either a fast G4, or a REALLY fast G3 on either a Beige, or a B&W G3 or Yikes!

Also, the tests they showed weren't that impressive...

Just from looking at the benchmark they posted it doesn't seem the second G4 makes a whole lot of difference over a single G4. The difference only amounts to about 12 or 13%, which you most likely wouldn't even notice. It's certainly not enough to justify the expense of buying one back when it was new and probably not worth the effort of trying to hunt one down now.

 

[TylerEss]

I've wanted one of those ever since I first saw them reviewed in MacAddict magazine so many years ago. If I had the opportunity to pick one of them up, I'd do it in a flash if the price was right, not because it's 'good' or even very useful, but just because they were obviously trying so hard.

 

[Franklinstein]

Multiprocessing on the PowerPC 7xx-series chips was difficult because, like the 603 they were based on, they lacked the proper cache coherency protocols and the like to support proper multiprocessing. It was possible to run a dual 603 (and Be, in fact, had one) and dual 750s, but it was extra effort required on the part of the system designer, and it wasn't really all that rewarding; it's like MPing with Celeroffs.

The PowerPC 7xxx series, however, like its 604 derivative, did have all of the necessary hardware for an MP design. Hence the reason these chips were used in multi-chip configurations from many different vendors, not just Apple and friends.

The memory/PCI controller used in the G3 line, the MPC106, could run in two different modes, according to Tundra/Freescale/Motorola's specs: it could either run a single processor with an external L2 cache, or run two processors without. It wouldn't go both ways; that's what the MPC107, the controller included with all of the G4s, was for.

As a side note, the MPC107 could only do dual processors, which may partially explain why nobody (AFAIK) has ever made a quad-processor G4 upgrade.

It's still pretty interesting that a dual 7400 would work at all on in an old G3. I'd be interested to know how they got it to do so, even if it was imperfect. Did anybody ever try one in a Yikes! G4?