I Love You Apple, But Sometimes…
Lately I noticed that the fan on my MacBook Air wasn’t ever shutting off. I ignored it as long as I could, knowing that it’s one of the MacBook Air’s (1st gen) known troublespots. I wasn’t seeing too much of a slowdown in the machine, though sometimes the CPU would spike. And, I know Firefox was the cause of at least some of this by paying attention to the machine’s disposition through the course of the day.
Last week, I got totally hosed on an online conference, my machine totally unable to keep up. Frustrated, I decided to dig in… two hours later I had a quiet machine without CPU spikes, and I’m going to share exactly what I did. I’m not a hacker, so hopefully my explanation in layman’s terms will help people who aren’t nearly so technical.
First, I wanted to see what was going on, and the seemingly best way to get that done was with iStat. iStat installs easily, is free, and with relatively little technical knowledge can tell you all sorts of things about your machine without ever opening a terminal. It also has links to Activity Monitor and Console apps, which give you quick access to important log files. I know these apps exist, but never remember what they’re called, so having them just a click away really helps.
Tells me my CPU is running very high, due to kernel_task. I look into this, and it basically means something is not behaving well… A quick google search turns up nothing specific so I go with my gut, and turn off Firefox. Turns out, it’s the culprit. CPU goes down when I quit it, and up when I start it. I often keep a lot of tabs open, perhaps that’s it. But… knowing that a lot of other people run Firefox on their Mac without any trouble at all, I start by deleting all my add-ons.
Normally, it would have been smart to disable one-by-one until a culprit could be identified, but I just wanted to get it done. I’ll go back later and enable them one at a time to see how the machine likes each. Add-ons can easily do something wrong; unlike the Apple App store, there is no one governing quality of firefox add-ons. (Of course, it also means there is no one telling us all what we can or can’t do either… two sides of the same coin.)
So, I deleted/disabled all my add-ons. And, surprise, firefox is better. I’ll have to go back later and re-enable the plug-ins I really want, and see if it’s one of them that were mucking with things.
That said, my fan is still running high, and loud. Constantly. And, restarting the machine quiets it down, but it’s not long before the fan kicks up again.
By the way, the machine is not sitting in the sun, and I’m in an air conditioned room of about 73 degrees.
I purchased and installed coolbook. Coolbook is an app that lets you undervolt your machine so the CPU runs cooler. This is a great article on using Coolbook, and also turned me onto SMCfancontrol. I used the settings in the article but for the highest frequency, because the test failed. So, I’m running 1.8Mhz at 9.875. In general, each CPU is different, and the article recommends how to test different voltage levels, but I’m lazy. If it works for him, .9v seems quick a good number.
If you’re interested in what Coolbook really does, there’s a great article on Macrumors.
I’m starting to think I might have two problems… first is it runs hot, then the fan turns on. Second is that once on, the fan doesn’t turn off without the machine getting unreasonably cool. I read somewhere that the fan doesn’t turn down until under 50 degrees C. Even now, not doing anything with no peripherals or second monitor attached, I’m running at 52 degrees.
Based on my reading, when the CPU isn’t being used (like it was for the firefox problem), it might be any number of things… could be my desk surface is not dissipating heat well (I’m writing on the desk right now and it’s staying cool, so that doesn’t seem to be it). It could be “all” the peripherals I attach. I’m going to need to see if this is the case… the key ones are the monitor, keyboard, and external hard drive. I’ve got bluetooth mouse now and no problems. Running with an external monitor and doing regular work seems to bump the temp up to about 70 degrees.
I also installed SMCFanControl: (if that link disappears, might want to look here: http://www.eidac.de/?page_id=6)
And, using the article above, I’ve set the minimum fan speed to 3800, since the article said that he chose his setting of 3810 which still had no audible noise… this way, the fan runs and cools things, keeping it cooler overall longer, before the higher fan rate kicks in. (After a few days of this, I see it doesn’t make a difference for me, for the most part, my fan just kicks up).
Reading the forum link above, it does look like powering an external monitor is a heavy load for the machine, and makes it run hot. I’m not willing to give that up. Though, it makes a huge difference, seemingly about 15 degrees C.
Once installing Coolbook, keep an eye out for weird behavior. Even though it works well initially, it may cause some instability to undervolt too much, and you want to keep an eye on that.
I need to look at max fan speed – because I’m now working on this an hour, and not running anything but Evernote and the Browser, and my temp is still below 49 degrees, but my fan is back up to 6000 rpm. I was hesitant to muck with the maximum fan speed, but this thing won’t shut up.
In one of the articles, one of the smart sounding guys said that he found “4000rpm to be absolutely sufficient on my machine and with my working habits”. That’s enough for me… though I’ll keep an eye on the temp to make sure I don’t fry anything.
I’ve just set max temp to 4000, and the fan went right down. Now, I’ll just keep an eye on the temperature. This needs to be manually set after each reboot, though it can be automated.
And, here’s a thread on the script to run it automatically (post #35/36 covers it, for boot and coming out of sleep).
I created SetMaxFan app in automator, put in Applications folder. Set it to run at startup, hidden, in Accounts/LoginItems. Works like a champ.
Installed SleepWatcher 2.0.5, and set the .wakeup script to the following:
#!/bin/bash/Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80
Can’t seem to get SleepWatcher working, but for now, it seems quite easy to pop a terminal and run the script manually when I hear the fan (which I always do if I working with the monitor attached).
In the end, I suspect it’s my external monitor that’s causing the heat in the machine. it’s a Viewsonic that’s about 3-4 years old.
I hope this is helpful. Enjoy the silence!
