Dealing with an Apple 1.25 Dual Processor


The standard Apple processors in the MDD need extra work to secure them. As you can see here, they need to be held in place as normally the heat sink does this. Two Aluminium posts were pop riveted at both ends providing a secure fixing that can still be rotated (as Giga Designs). This then allows the two screws to be replaced, that held the original heatsink & processor in position.


The next problem you are faced with is that none of the fixing plates supplied are anywhere near to fitting the standard Apple processor.


Once again something has to be manufactured (see above right). This time I went for stainless steel as the fixing does not have to come into contact with the processor chips themselves, but must provide support & not rust.


Drawings for these parts are on PAGE 6, available for Download as pdf's.


This then holds the 8mm copper shim in position. One problem that has arisen is that some early MDD's do not have the 4 holes required for mounting the original stainless steel plate. It is important to check to see if your processor is one of these, if so I have drawn up a new universal plate design that uses the 3 large holes that can be seen in the photograph above, a drawing of this can be found on PAGE 6. This plate design should fit both early and late processors.


You will also need to make some 8mm standoff's to fit between the stainless steel plate & the processor - see the downloadable pdf's on page 6.

These were made from small bore aluminium tube, available from B&Q or most good hardware stores.


If you want to overclock your dualie there is a brilliant web site here that gives you all the settings,




I now have this up & running & overclocked to 1.5 Gig. Not bad for a processor that started life as a Dual 1.25. This needed various resister changes to run at this speed & a voltage boost from 1.55v to 1.60v.


This is achieved once again by visiting "Bits & Pieces" website. This does run hotter than the Giga but is a stable 33 degrees.


It is difficult to tell the exact temperature of the Giga as it has no thermistor on board. Getting as close to the chip as possible with a Lian Lee thermometer reveals 29 degrees on the Giga. However I would suggest this is lower than a true reading at the centre of the processor core.


These figures are with Chud 3.5.2 installed.




This puts a Hardware Icon in your System Preferences, you must enable the Nap checkbox.


This works perfectly with Tiger.


I've now made a little Apple Script that enables Nap by default on dual G4's, this is also available for Download on PAGE 6


All in all I'm really pleased with watercooling, I've always thought it would be too problematical in the past, but it was actually surprisingly easy.


The most important thing to bear in mind is to really take your time planning.


The drop down door on the G4 needs carefull consideration but can be made to work successfully. When it does work the feeling of achievement is all the more rewarding.


Future Plans!


I would like to watercool the video card but need to find a cooler that will cool the memory on a 6800 & not just the chip. Till then.......

Shown to the right is a modified Stainless Steel Plate That can fit Apples alternative processor design - The one without the four holes or, all 7 Holes can be used, as shown by the bolts in the drawing.


Universal Stainless Steel Plate Drawing


More MDD Watercooling 1


More MDD Watercooling 2


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