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-   -   MDD Dual 867MHz CPU Overheating (http://www.mac-forums.com/forums/apple-desktops/117863-mdd-dual-867mhz-cpu-overheating.html)

rfhandel 07-30-2008 03:13 PM

MDD Dual 867MHz CPU Overheating
 
MDD Dual 867MHz CPU Overheating

I have noted the large number of problems with this particular model and heat issues, but I just received this stripped MDD to do an upgrade on the cheap for my B&W G3 server. In hindsight this might not have been the best unit to upgrade with, but for $72 on ebay (seller was unsure it was dual processor--which may have helped lack of bidding), I figured it was worth it.

After putting RAM to 2GB, putting in an ATI 9200 PCI graphics card, and inserting my HDs from the B&W with updated Tiger installed, everything booted fine with no problems. Dual processors checked out, RAM was fine, and all drives loaded without glitch.

Next go round, after 20-30 minutes it does the sleep/freeze thing everyone has mentioned here and elsewhere. All fans work and have tested with door open and high speed fan directly over heat sink and it still shuts down. Temperature Monitor has it rising above 80c and climbing, which I no longer let go until "closing" to avoid any more damage.

The weird thing about this is that during all of this, the aluminum heat sink remains relatively cool, as if it is not making any contact.

Is it possible it just needs a pad or compound to make contact and dissipate the heat through the sink etc., or does this sound like either a faulty sensor or failing CPU? The compound would be an easy fix (and it sounds logical), but I may just be missing the obvious here. My hope is that the prior owner just did not bother to find out why it did this and cannibalized the unit.

I could take out all the drives, etc. to reduce the heat build up, but I want this to function as a feasible house server that can be left on most of the time + because of the cool heat sink the behavior does not seem to relate to the heat in the housing.

Any and all help will be most welcome.

louishen 07-30-2008 04:27 PM

you can monitor the CPU temp with this

http://www.versiontracker.com/dyn/moreinfo/macosx/19994

Thermal paste may be needed as you say, also what is the temp in your house

rfhandel 07-30-2008 05:41 PM

Temps
 
Quote:

Originally Posted by louishen (Post 700869)
also what is the temp in your house

W/AC in Florida summer about 78F. I have Temp Monitor--which is how I ascertained I had a problem. I am just assuming that since the heat sink is cool to the touch, no heat is being transferred from the processors. I am going to go ahead and clean/apply new layer of thermal paste, but am just curious if the writing is on the wall that these babies are already fried. I have also thought about getting the copper heat sink for the faster MDD dual CPUs, but do now want to chase good money after bad.

harryb2448 07-30-2008 07:40 PM

http://macosx.com/forums/mac-os-x-sy...e-problem.html

Firstly make sure the inlet and exhaust ports for the MDD are cleaned regularly and use a paint brush to clean the fins of the heat sink. Make sure all fans are working as early models did have fan failures.

You mention PCI graphics card - do you have an AGP card which are up to 2x faster? Core Image compatible cards such as the ATI Radeon 9600 do not require a fan unit asnd run cool and quiet.

Temperature Monitor is a free download and will advise what the actual CPU temperature is. From memory Apple Discussions advised 65 celsius was the danger point and brought on system freeze.

Also the reapplication of thermal paste, use Arctic Silver, will help if this has dried out and cracked. Hope it comes good for you.

rfhandel 07-30-2008 11:32 PM

I bit the bullet, went to Radio Shack and got Arctic Silver 5 compound, cleaned off the heat sink and processors with a credit card and alcohol as suggested on their site, screwed everything down, kept the door open with a fan pointed right at the heat sink, turned on and prayed.

With the door open and fan on, I am maintaining a 50.5-51.4C temp. When I close up and let the original (and annoyingly erratic) fan do the work, it maintains between 59.5 to 60.5C. This suggests I need a better fan, but I guess the old paste was just preventing any heat from conducting through to the sink. Time to do a mod on the fans. Hmm, should I really get adventurous and liquid cool it--or overclock it? I guess I should first get some mileage out of my fix before I break it.

harryb2448 07-31-2008 12:28 AM

This will help when you are ready for the jon"-

http://startoftext.com/?p=99


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