> There is no hard disk, so it does not heat up,

It's not the disk that gets hot, but the CPU. CMOS transistors draw current only when they switch, which means that the faster the clock speed, the more current and the more heat. Haven't tried the Air, but at 2.4GHz flat out, my CPU hits 80 degrees and the case is uncomfortably hot. When I run a BOINC background calculation (SETI, climateprediction, &c), I set maximum usage to 50%, both for comfort and for component lifetime. Even so, it runs cooler than my earlier model, which regularly shut down in the summer. Every tick (or tock) of the Intel clock shrinks the chip size--the tocks (or ticks) improve the architecture--and the current drawn and the wattage of the power supply, which all translates into cooler CPUs and knees.

Text processing uses very little CPU time. Normally, running Nisus, the laptop is comfortably warm--a boon in my house, since we still haven't gotten the solar hot-water system connected, and two cats are no warmer than one, since (after 6 months) they still wish the other one would just go away.

Having said all that, I look at Activity Monitor and find network activity even when Airport is shut down and ethernet unplugged, and frequent bursts of 100% CPU usage and disk activity by Finder, with 3 threads and 80 processes. None of this do I understand!  Photoshop, open, but hidden in the dock with no display, occasionally uses 10% of CPU time. Why is the Finder so busy? To whom is he reporting what?

-- Ferren
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(Dr) Ferren MacIntyre   1 Chemin des Echarts
Campagne sur Aude     11260 France
42.91500N, 2.20900E    +33 (0)468 748870
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OSX 10.6.5  MacBook Pro 5,1
2.4 GHz Intel Core-2 Duo, 4 GB