I have used a few MDDs.
The only difference everymac is telling me is the L2 cache. The 1.25 DP got 2MB while the 1.25 SP got 1. Is the 2MB of the DP for both CPUs or 2 MB per CPU?
Then I wanted to know where the Cache is located. Is it at the G4 daughtercard? So do I swap the L2 when I swap the CPU?
Now that you mention it, I don't know for sure! I have been assuming that there is 1MB cache on the card for each 1.25 CPU, being why the dual is 2MB.
Are there any other differences of the mainboards. Systembus is the same as the RAM controller and IDE, ...
Last question, can I put every MDD CPU in every MDD? I got a broken 1.25 DP around. As the SP 2004 model was available BTO with a DP CPU, I think so, but I would like to get it confirmed.
Anything else what I didn't think about and why I should go on seeking for an original DP 2002 model, as it brings more performance in any area?
They are all nearly identical, with one big exception - not all 2002 G4s are the same. The dual 867 MHz M8787LL/A model is IIRC the only MDD to use a slower 133 MHz system bus, compared to the usual 167 MHz. Both the dual 867 MHz and dual 1 GHz have less L3 cache than the 1.25-1.42 models - 1 MB total for both processors. But, as I said, I am guessing that these caches reside on the CPU cards, so they would then get swapped out with the processor. There might be some sort of multiplier hack to enable a 167 MHz bus on these slower systems, but I have not looked into it.
As for other details of the logic boards and chips, I have not noticed any significant differences, apart from the entry-level 133 MHz bus, and the later FW800 which does not natively boot OS 9. Somebody with better eyes than me could perhaps compare the chips on the board.
In my experience, all of the MDD CPU cards are inter-operable. I have put a few of these systems together for people over the years out of spare parts and experienced no anomalies. Also, the MDD CPUs can be exchanged with those from Xserve G4s, but the heatsinks are not compatable so you'd still need a MDD/FW800 heatsink. The copper heatsinks are more effective than the aluminum ones.
Ah, ... and the machine would have got two 1GB RAMs working well with X. Might that be a problem for 9, or is it only connected to the hardware itselve?
It's a tricky question that might depend upon what OS 9 software you use. You can install up to 2GB of RAM in a MDD tower, which makes OS X much happier. If your OS 9 system is stable with the extra RAM installed then this is the easiest situation. But if there are stability problems or programs crashing I would try running it with only 1GB. Since my current system is used almost entirely for OS 9, I have only 1GB in it now for simplicity.
Topic: MDD consultation needed (Read 5855 times)