Mac Air Fan, Boy!

So I guess I should confess that I've got a Macbook Air.

One of the first generation models, with the smaller disk and the less-capable graphics card, so Lewis's had it at about a third off the price of the current one.

It's nice in many ways, though at times it does tend to get rather warm, and, when the cooling fan ramps up, distinctly audible.

That wouldn't make much difference to me, since I mostly use it for typing text and occasional bursts of web surfing, except that it can be driven to working hard by, say, a flash animation running un-noticed in a corner of an off-the-screen Web page. So I've got into the habit of making sure I avoid such things. But still, sometimes, the machine starts to get warm and "noisy" (well, OK, noticeably not silent :-) for no apparent reason.

When this happened the other day, I took the time to investigate. And discovered, eventually, that part of the sound system (coreaudiod) was using over 10% of the CPU, even though there was nothing that used sound being run at all. Moreover, Mr. Google showed me that other people were also observing this same phenomenon. It seems that it is prone to running away like this under some circumstances. The problem is present in Snow Leopard, too, and can be triggered by "any" application that uses audio --- even a terminal window (can you say "bell"?)

I also found a command to restart the daemon:

sudo launchctl stop com.apple.audio.coreaudiod

I tried it, and the new incarnation of the daemon was as lethargic/inactive as you'd hope for an audio daemon on a machine being silent.

Straight away, the CPU temperature started to fall, as in due course did the fan speed,

So it seems that the 10% load was enough to keep the CPU fully powered up, and thus fully heat producing...

Good, eh!

Robert.