Question regarding a heatsink

[mac-man6]

Hello everyone, a while back I picked up a G4 MDD and gave it to my sister. There's a thread on me trying to diagnose it, what it's worth and yadda yadda yadda. Fast forward 6-7 months the MDD is acting funky, freezing and wont wake up, some PCI slots don't work and the front button doesn't work reliably either. I picked up a Quicksilver and another MDD (because it was a package deal) for a Hackintosh in a Macintosh case idea. I ditch that idea and try to fix my sisters computer. The previous owner gutted everything useful out of the machines but still listed them as macs. If there's no processor, ram, video card, battery or optical drive. I think it doesn't count as a mac anymore - it's just a case with a logic board.

, spiel, backstory>

Today I swapped some things around and got a better behaved MDD (wakes properly, front power button works, PSU seems quieter). Does it matter what kind of heatsink I use on a single 1.25 ghz processor card? The single heatsink is apple part # 805-4579 or the double processor heatsink apple part #805-3300. The double heatsink has a lot more aluminum so I assume it would be just as good or better at dissipating heat. So does it matter what kind of heat sink I use?

Lastly, I'm sneaking in a second question. Both MDD's have 1.25ghz processor cards with identical apple part #s. One is on green motherboard material the other on blue. I was using the blue card before and I could retrieve the heat sensor data. I put the green in today and I can't read from the heat sensor anymore. When I started up the temperature monitor from http://www.bresink.de/osx/TemperatureMonitor.html they said I changed processors and do I want to bring over settings. I said yes and now it can't give me a temperature. I'll try trashing the preferences before I try it again. Do you think this is a software issue or an issue with the daughtercard?

 

[Bunsen]

Try redoing the heatsink thermal transfer paste.

 

[mac-man6]

For those curious, I've trashed the prefs and it didn't help. I switched back to my original 1.25ghz daughter card and the software recognized the heat sensor. Under the previous card it sound like the fans were randomly slowing spinning up and down, like it didn't know what to do. The original card had the computer run the fans at a more consistent speed.

And for the very curious, it doesn't seem like there's any harm using a dual processor heatsink on a single processor card. It works just fine.

 

[khmann]

Word on the street (the seedy back alley archives of the internet : ) has it that the thinner finned heatsink is the better one, almost as good as the copper one used with the 1.42 DP. Apple very specifically says both are "equivalent" in their service documentation. From what I have seen the thin finned one is less common.

Regarding the CPU's, they might both be dual 1.25 but there were at least two versions - 1MB cache per processor (7455b) and 2MB cache per processor (7455a). There may also be a difference in the cache:CPU clock ratio. The 1.25/1MB processor was the later version and uses 7455b which should be able to run at a lower voltage (less heat) and possibly overclock higher.

 

[Tron]

I'd tested the three heatsinks in my MDD overcloked, where the little diferences are more apreciables.

This are the results:

"thinner finned heatsink"...... 0 C

"Aluminium monoblock".........-1.70 C

"Copper from 1.42"..............-5 C

Regarding motherboards, I think the blue, are the modern ones, or at least more news.

Sorry for my bad English

 

[mac-man6]

Thanks for the info, what's your normal operating temperature?

 

[Paralel]

I guess I will have to think about shoving one of those copper heat sinks in my MDD if it gives that much of a temp. drop.

 

[MacJunky]

What thermal compound were you using for those numbers you listed?

 

[Tron]

I'm using Artic MX-2 thermal compound. Its very good but be aware, because is a little capacitive, dont touch the capacitors near de CPU.

I don't know the normal operating temperature now. Because a have several parts of MDD G4 (3 heatsink, 3 CPU módules, 3 motherboards, 2 cases etc..). I was experimenting overclocking up to 1.7 Ghz. When I have to test the heatsinks one year ago, just swap the 3 ones in the same system and only take note of the diferences. I don't remeber the absolute values.

Now I write this from a 1.5 dual at stock voltage (1.42 overcloked). I have it for a year whithout a problem due to verclock. I don't have OsX instaled so I can't read the actual temperature.

More over, I usually put a second little fan in to the back of DVD-ROM that sends air to the heatsink, completing the original fan,cooling very well this machine, and its very easy to install.

But overcloking, core voltages, temperatures and cooling MDD may require its own thread

Sorry for my bad english.

 

[MacJunky]

I'm using Artic MX-2 thermal compound. Its very good but be aware, because is a little capacitive, dont touch the capacitors near de CPU.

I use MX-2 in my PCs and Macs (using a 30gram tube atm ).Arctic Cooling advertise it as non-electrically conductive and non-capacitive. And with no cure time(both advertised and observed by usage) those are key selling points for it over Arctic Silver 5.

Do you have personal experience with it's capacitance or if not, where was this test done? I would like to read it. Not that I have a problem with spilling it everywhere, I just would like to know if I might have potential for issues when using it with CPUs without integrated heat spreaders.