Frustrated with the heat build up in my new Mac Dual 1.25, I decided to investigate the idea of replacing the aluminum non-heat pipe heat sink with the 1.42 heat pipe heat sink. First I had to acquire a heat sink for a 1.42, Apple does not sell them as a customer installable part. Using my head I got one. (Update - the Apple part number is Part No. 076-0983 and depending on the dealer may be available for less than $100, William later wrote that the apple list price may be as low as $65 plus shipping/applicable taxes, but prices may vary by dealer. The part number of the heatsink is reportedly 076-0983 but verify that when ordering.-Mike.)

Here is the one I want to replace. Verax has a kit they will soon have available but $269.00 for the complete kit seems a little steep. The Verax kit does include replacement fans for the power supply and CPU. The kit can be viewed at the following site: http://www.veraxfans.com/.

Here are the two heat sinks side by side

As you can see the 1.42 heat sink has a heat tube built into it so it provides optimum cooling of the twin processors. All of the mounting holes line up perfectly, no modifications had to made.

Simply unscrew the old heat sink retaining screws and use some thermal heat sink paste to apply to the processors before mounting.
You can get the thermal paste at Radio Shack. (Note: some will prefer to use Artic Silver compound)

Here is the Mac Dual 1.25 without the heat sink. Note the residual heat sink paste.

You want to make sure you apply enough paste to both processors. DO NOT over do it!

Do a test fit to make sure the heat sink and the processors are seating properly, THIS IS VERY IMPORTANT! YOU COULD FRY YOUR PROCESSORS IF YOU DO NOT SEAT THE HEAT SINK CORRECTLY! The picture indicate that all is seating correctly, as you can see the heat sink paste has left residual on the heat sink, indicating a proper fit.

Final result: Copper heat sink with heat pipe installed. This should resolve any heating issues with the inside of the Dual 1.25.
(he later wrote)
Here are the heat ranges:

• DVD-ROM Bay 100F
• HD Bay 80F
• CPU Base (Heat Sink) 110F (was 120F w/Alum HS)

(Temperatures can vary depending on CPU load, ambient temperature, etc.)

Total out of pocket expense $100.00 (or less)

Remember, this could VOID your Apple Computer warranty. Perform at your own risk.
-William

For other MDD System related articles, see the Systems page.