Hi Tarbos,

Thanks for the comments. I wasn't aware of capillary forces being used for heatpipes too. Probably my old study books are outdated. Sign of time

I'll use the RC5 client next time. I don't have it yet. Does it use Altivec? I did do a test using 100% CPU load for 30 minutes and the temperature difference was less than 1 degree off from the 60% CPU load test playing a DVD. But I don't have MorphOS programs that use Altivec (yet).

You're right it's not likely that the CPU will die immediately if it's used aboved its maximum operating temperature. Actually, I never tested it as I don't like to waste my money on destructive tests... I leave that to the manufacturers.

Most probably the CPU will show erractic behaviour long before dying. Which can be solved by turning it off and let it cool down. But if you keep it running hotter and hotter, you're likely to do irreversible damage. Temperature related changes in silicon device parametrics eventually will make one of the very tiny semiconductors in the CPU exceed maximum current and fail forgood.

I simplified my post because I felt it was already lenghty and didn't want to bore all of you with details.

For those who are interested in MPC7447 related documentation, you can find it here (well as long as Motorola hasn't spun off its chip division):
http://e-www.motorola.com/webapp/sps/site/prod_summary.jsp?code=MPC7447&nodeId=02VS0lXvDCRtk68653#documentation

If you really want to know:
The 35,2 Celsius came from a calculation in Motorola's MPC7457EC (electric characteristics) document. The junction-to-case thermal resistance of the MPC7447 in CBGA package is 0.1 K/W. The thermal resistance of the interface material between device and cooling solution is assumed to be about 1.5 K/W.
So at the maximum rating of 22 Watts this results into a 22*(0.1+1.5)=35.2 Celsius temperature difference between the actual cooling solution and the junction.

Oh, before I forget: you don't need to buy an extra CPU thermometer. One is included inside the G4 (and G3) already. But I was too lazy too write code for it as it was more than one page of programming...