Thermal Paste in MDD?

So I'm on the last of my upgrades to my PowerMac G4 Dual 1.25 MDD and its the copper heatsink.

I've been looking around on the net and checking out how to replace the heatsink and it seems simple enough. Although the issue of thermal paste is beginning to confuse me.

I did some searching around on the forums and it appears that many G4's didn't require thermal paste, which made me wonder, does the MDD? I would think so due to its history of heat issues. However I thought I would ask you guys since you're the experts =)

I've also become aware of the debate of not spreading thermal paste (and letting the heatsink do it) vs. spreading it with a credit card or similar object.

You learn so much when upgrading a mac, yet end up with so many questions lol

I'm not familiar with a MDD and can't really answer your question regarding whether or not they use thermal silicon paste (heat sink compound) on the heat sink. However, being in the electronic repair and computer repair fields for many years, It's rare to come across a CPU heat sink that doesn't use thermal paste for efficient heat transfer.

The ideal though is that the correct amount has to be used. Too much causes bubbling and cracking which can lead to damage while too little does not provide enough heat transfer from the CPU to the sink to be effective.

Actually, a very thin layer evenly distributed is all that's needed. Go ahead and apply some, as long as it's done correct.

Regards.

Thanks for the input! =) I felt that it would need some. Do you have a method of application which you recommend? Is it better to apply a thin layer to the cpu and spread it out, or simply drop a rice sized amount and let the heatsink spread it upon contact?

I've always used the "thin layer spread method". The surfaces between the heat-sink & cpu are pretty darn flat...so you usually don't have a problem getting good contact.

If you use the "drop method"...when you assemble things...the "drop" may spread in an unpredictable manner...and some may ooze out one side unexpectedly (making a small mess). And 100% of the heat-sink/cpu interface may not be covered with paste.

- Nick

Just installed my copper heatsink using the spread method and AS5. Up and running right now =) Thanks!

XMARLTONX said:

Just installed my copper heatsink using the spread method and AS5. Up and running right now =) Thanks!

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Awesome!!!

- Nick

I've always used the "thin layer spread method". The surfaces between the heat-sink & cpu are pretty darn flat...so you usually don't have a problem getting good contact.

Click to expand...

I second what Nick stated above. The only time I've ever used other methods of spreading heat sink compound was on high output audio transistor circuits which use a silicone wafer for insulation from its aluminum heat sink.

Regards.

That seems to be the best method from what people have been saying, there's just so much out there in terms of information and opinion when it comes to this it's hard to nail down who's right sometimes. Thanks again for all the help =)

XMARLTONX said:

That seems to be the best method from what people have been saying, there's just so much out there in terms of information and opinion when it comes to this it's hard to nail down who's right sometimes. Thanks again for all the help =)

Click to expand...

Hey...if someone had the time to do the research (drop method vs. spread method). Then test the cpu temps & longevity of each method afterwards...if the temps were the same...and both methods had the same longevity...then maybe both methods would be equally effective.

But the big "???" with the "drop method"...is exactly what size drop do you use (heat sink & cpu surfaces can be different sizes)...and with the "drop method" you never really know how the drop is going to spread when the parts are assembled. 100% of each surface probably won't be covered...and you may get some unexpected "oozing" out the sides.

- Nick