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I picked up a MDD that was reportedly having stability issues. It is a 1.0 GHz DP. It would kernel panic a Mac OS X Leopard immediately after booting. I then found out that the original high speed Delta CPU fan was replaced with one slow xsilence fan. Of course, the CPU would got very hot very soon, so I bought a replacement original Delta. I also blew all the dust out of the case with a compressed air, however it wasn't really dusty. Next, I replaced the thermal grease on the CPU with an AS5. It runs solid as rock now, but still it is running too hot.

 

The problem is that the CPU idles at about 58 deg. C (135-136 F), at load it is almost no difference even after some time. I believe that this is too hot, since the main fan is running at almost full blast. I also found out that when I open the case, the temperature drops to about 48 degrees C (idle). I believe that the contact of the heatsink to CPU die is somehow lost when it is placed in upright position, but when the case is open, the weight of the heatsink pushes it down and it again makes a good contact.

 

Any ideas what should I check?

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I am not sure how hot MDDs normally run but have you made sure the fan you installed was pointing in the correct direction for the MDD case?(and not just the same direction as the previous aftermarket fan was installed) Also, have you checked any other fans to ensure someone did not screw around with them as well?(again, IDK how many fans a MD actually has)

 

At the end of the day though most of Apple's cases are not really known for good airflow.

 

To test your heatsink theory you could close the case and rest the whole thing on it's side, but unless someone altered the mounting hardware it is probably fine. You would be surprised what you can hang sideways!

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I use a Hardware Monitor application. The room is 22 deg C. Well, the sensor does seem to work okay, since when it is first started, the temperature is nice and low at 32 degrees C, then it starts to rise. Also, at first, when it was crashing, the temperatures were about 65 degrees. I correctly oriented the fan. PSU fans were replaced with quieter ones. Original ones were 37 CFM, these are 30 CFM.

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I use a MDD G4 867mhz as one of my regular "use" machines, so I have some advice.

 

First is downgrade to 10.4 - Tiger.  The reason -- to get the temp down you need to use CHUD 3.5.2.  This allows you (automatically) to enable "nap" mode which steps down the processor's power in steps depending upon how busy the processor is (just like laptops do).  There is a startup script to automatically enable nap mode - but it doesn't work properly under 10.5.  You can manually turn on nap mode with 10.5 but it gets very annoying very quickly.

 

Nap mode makes a "HUGE" difference.  My MDD isn't as fast as yours but still I was experiencing temps that were on the verge of a meltdown before I did this.  Another option is to add some papst fans in there to help with the circulation a bit. 

 

So:

 

1. Install 10.4.11

2. Install CHUD 3.5.2

3. Install the CHUD nap mode script into the hdd, set it to a startup item in the control panel under your user account.

4. reboot

5. Enjoy a lower temp, reasonably usable MDD G4

 

Send me a PM if you need any of the files.

 

 

I use a Hardware Monitor application. The room is 22 deg C. Well, the sensor does seem to work okay, since when it is first started, the temperature is nice and low at 32 degrees C, then it starts to rise. Also, at first, when it was crashing, the temperatures were about 65 degrees. I correctly oriented the fan. PSU fans were replaced with quieter ones. Original ones were 37 CFM, these are 30 CFM.

Edited by lopaka1998
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