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MAD SCIENCE: Homemade Heatsink
for iMac G5 Hot Hard Drive

Posted July 1st, 2005, by rob-ART morgan, mad scientist
Contributed by Hart Hansen, remote mad scientist

We reported in Quick Takes on June 20th about the discovery by Hart Hansen, one of my "remote mad scientists," that the 400GB internal hard drive of his iMac G5 (rev B) measured at 89C/192F on the surface. By comparison, the same model of 400GB drive installed in our G5 Power Mac measured 47C/116F.

Most drive manufacturers recommend a maximum "ambient" operating temperature of 55C/131F and maximum top surface temperature of 60C/140F. Extremely high operating temperatures have been proven to cause premature drive failure. If your drive is operating above those temperatures, you should be concerned about drive failure and data loss!

Hart decided to take matters into his own hands and try some mad science. He created a heatsink from aluminum foil, thick paper, and a PCI slot cover. By popular demand, I'm posting the pictures he sent me.

Remember the surface temperature at 89/192F? After installing the homemade heatsink, the surface temperature dropped to 41C/105F. If it's that easy to fix, one wonders why Apple engineers didn't do something to dissipate the heat better. I know they know how to cool drives in tight spaces -- my PowerBook 5400rpm drive never gets over 44C/111F.

One drive manufacturer told me it's the responsibility of the computer manufacturer to insure that the surface temperature of the drive is within a few degrees of the ambient temperature.

In the first photo above, Hart circled drive temperature sensor built into the iMac G5. You can sample its readings with software (like ThermographX and Temperature Monitor). Both will give you the ambient temperature near the drive since the sensor isn't touching the drive. If your drive is S.M.A.R.T. rated, Temperature Monitor, will tell you the internal temperature of the drive. That's even more informative than the ambient sensor.

We'd love to hear from you if you've got an iMac G5 with a S.M.A.R.T. rated drive temperature reading from Temperature Monitor. Email me, , with your results and the model of drive reported by System Profiler or Xbench.

If "rolling" your own heatsink doesn't excite you, I'll be making an announcement in a few days of where you can get a commercial heatsink for your iMac G5 drive.

The heat issues don't stop with the hard drive. I've also received reports of the iMac G5 CPU running a lot hotter than the G5 Power Mac CPUs. One remote mad scientist (RMS) wondered aloud why Apple didn't use an external power supply (like the Mac mini) and use the space saved for cooling pipes and a heatsink for the drive and CPU of the iMac G5. Another RMS said heatsinks are fine but there needs to be better airflow through the iMac -- like Apple (or some third party) should find a way to utilize the vents at the bottom and top of the iMac G5 to more efficiently move the air in the bottom and out the top. Stay tuned, we may have an announcement about that issue, too.

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2005 Rob Art Morgan
"BARE facts on Macintosh speed FEATS"
Email , the webmaster and mad scientist