Ah, that was extremely helpful; thanks! I assume, then, that G4 processors up to ones from the Digital Audio machines would be immediately compatible? I'm not sure what I'll go with yet, but it's good information to have. Also, could you please detail a bit how you got the 12V feed to the extra screw? I want to know what you did to have it working so it wouldn't disconnect or otherwise be a problem, as well as where you drew it from. Thank you so much!
You are going to need to tap into power from one of the Molex Power Supply cables intended for Hard disks or CD / ROM drives.
The yellow wire is +12v, and is the wire you need to somehow tap into, and run to the 4th screw hole. In my case, I had a dead Auxiliry CPU fan for a PC, that plugged directly into the molex power supply source. I then cut all but 1 of the wires free from the fan, and used the remaining wire as my power for the CPU, putting it into an eylet that I could bolt to the 4th mounting hole on the Quicksilver CPU
I used a simple PC case screw, and a nut that fit the threads ( I have stuff like this lying around
) and attached it to the 4th mounting hole of the Quicksilver CPU.
You need to be careful to ensure this 4th screw and nut does not contact the Motherboard, or touch the heat-sink. If it does, it can short out, causing bigger problems. So put a small square of adhesive backed rubber sticky pad on the logic board near this 4th point, and modify the CPU heat-sink if needed.
You may also have to do light case modifications to allow for the Quicksilver heatsink to clear your CD-ROM / ZIP drive cage. You May be able to keep your old heat-sink depending on the speed of processor you go with, to avoid this though.
this is interesting, since it is not covered here
http://lowendmac.com/mail/0803mb/0306.html#2 (restrictions in spapping G4 CPUs).
I recently wondered, if a last generation Quicksilver and first gen. MDD would be interchangeable, since the BUS-speed is the same and the other MDD models all seem completely different by looking at the specs. In fact I wondered, if the first MDD, was just a Quicksilver in an MDD-case.
I guess I don't know what that guy is on about for part of that post, but the only reason you would need to do any electrical modification to the processor, is to change it's multiplier to match the older systems 100 MHz bus speed. Bolted down, and given the correct power, the CPU will work fine, but be slower on the older 100 MHz Bus. You can change resistors around to increase the multiplyer on the CPU to a higher rate, but I don't know which resisters you would move / change to do this sadly
.
Without modification you can calculate what a CPU from a 133 MHz Bus PowerMac will run, on a 100 MHz Bus system
Say we are working with an 800 MHz Quicksilver Processor
(800Mhz * (100/133)) = 600Mhz
I have zero experience with the MDD systems sadly. I am not sure about processor compatibility with those. There are quite a few write-ups on installing Quicksilver CPUs in older systems, but I have never seen one on a MDD CPU.