There’s been a number of complaints in forums about MacBook Air heat problems and fan noise or fan running constantly. What causes these heat issues? What’s the fix? Does it affect the i5 model as well as the more powerful i7?
This article addresses fan noise and heat issues with the current MacBook Air 2011 / 2012 models, released mid-July 2011.
Here’s a video a Mac Crazy user sent in of watching video online with his MacBook Air i5 13 inch. The fan is loud!
(Thanks to Rajulun for sharing this view with Mac Crazy – you are a star!)
First, lets start with a bit of background of why the MacBook Air get hot and why it has a fan. The MacBook Air has one fan inside it, at least in the late-2010 & mid-2011 models. The fan’s job is to keep the MacBook Air’s chips from overheating by pushing hot air out the exhaust port. The exhaust port is behind the keyword, at the screen hinge.
The MacBook Air fan runs constantly by design. The fan runs at or above a minimum speed while the MacBook Air is running. On my late-2010 MacBook Air 11 inch, the minimum speed is 2000 revolutions per minute (rpm).
At this minimum fan speed, during use, the fan can’t be heard by most people. If you put one ear to the keyboard, you can hear the fan. Some people, in a very quiet room, with very sensitive hearing, may be able to hear the fan at the minimum speed.
When the MacBook Air is busy it generates more heat. The fan then runs faster to keep the Mac cool. At higher speeds, you can easily hear the fan.
This is a normal cause of fan noise on the MacBook Air – MacBook Air is busy, fans are keeping it cool. Fan noise is like sweating – it’s a response to strenuous activity.
Examples of activities that make the MacBook Air busier are:
- running many apps,
- using web sites with animation (Flash) or video,
- playing games,
- playing or editing video, particularly HD video
The room temperature will affect how fast the fan will need to run to keep the MacBook Air cool. In a hotter room, the fan will need to run faster.
The highest fan speed on my late-2010 MacBook Air is 6500 rpm. You can check your MacBook Air’s fan speed with the free iStat Pro dashboard widget. iStat Pro will also measure the internal temperatures of your MacBook Air.
If you have constant fan noise, and your MacBook Air is not doing heavier activities, your Mac’s System Management Controller (SMC) may be confused. You can fix this with a SMC reset.
The hottest temperature on the bottom of the case I’ve seen quoted in the press is 105F / 41C (AnandTech) and in the wild is 109F / 43C (thanks for commenting Corbin). This benchmark was running Half Life 2 Episode 2, which works both the main processor and the graphics processor – both of which generate heat. Both processors are on the same silicon chip in the new MacBook Air.
(If you have a higher MacBook Air 2012 / 2011 bottom case temperature, please take a screenshot and leave a comment below.)
If your MacBook Air is getting too hot, there are some possible fixes below.
The fan noise and heat issues are affecting the i5 MacBook Air as well. Complaints of the MacBook Air heating up, overheating and fan noise are not restricted to the Intel Core i7 MacBook Air. I’ve had a reader send in a video of his MacBook Air i5 with a loud fan.
There are at least several possible causes for the MacBook Air high heat and noisy fan:
- Software functions that consistently use CPU are being used, e.g. video encoding, finding faces in iPhoto.
- Apps or other software running in the background is consistently consuming CPU.
- Adobe Flash, the technology used to deliver some animated ads in web pages and most web video is consistently using CPU. This is a specific, common case of the cause above.
- Software runs at startup that is not compatible with Mac OS X Lion. The software keeps trying to run and keeps falling over causing load on the CPU.
- The MacBook Air’s System Management Controller (SMC), responsible for controlling the fans, has become confused.
Cause #1: Software that Consistently Uses Processor
Software that is performing an activity that consistently uses can cause the MacBook Air to get very hot and the fans to run loudly. A few examples of heavy software are:
- Video export, encoding or format conversion (transcoding). For example, Handbrake for converting videos for display on iPhone or Apple TV.
- Importing photos to iPhoto or performing recognition of faces in your photo library.
- Playing some HD video. How much processor video playback uses depends on many factors, including video resolution (720p, 1080i, 1080p), frame rate, detail in video (bit rate), how sophisticated the encoding is (e.g. high profile), the video player used to play back the video, and how the video player is configured! Generally 720p is fine, 1080p is fine if it’s a lower bitrate Quicktime H.264 movie playing back in Quicktime, and other 1080i or 1080p (high bitrate or non-Quicktime format, e.g. MKV or AVI) will get the MacBook Air hot and fans will run.
- Playing web video. Web video uses Flash, and Flash video playback is less optimised than Quicktime. I’ve noticed that occasionally a web videos use several times more CPU than another at the same resolution. I suspect that is because some web videos uses formats that Flash is optimised for (probably H.264), and others use formats that aren’t optimised in Flash (probably non-H.264 Flash video ‘FLV’). I haven’t confirmed this.
- 3D rendering (e.g. Cinebench).
- Video editing and effects (e.g. Final Cut, Adobe Premiere, After Effects).
- Exporting a music track (mixdown), from a multi-track music project.
- Playing 3D games (e.g. Portal, Half Life).
- Running benchmarks.
If you are doing sustained processor intensive work expect it to get warm or hot and for the fan to become audible or noisy. Using either the main processor (CPU) or graphics processor (GPU) generates heat.
In these cases that MacBook Air is usually performing normally. Some of the heat is dispersed to the case, so the case feels hot. The fan speeds up pull cool are in and push hot air out of the MacBook Air.
Cause #2: Software in the Background Consistently Consuming CPU
Every application running in the background uses power and heats up the MacBook Air. If you use less battery, your MacBook Air gets less hot. If it gets less hot, it doesn’t have to use the fan. And on the way, you might double your battery life.
Note that it’s not just apps running in the background that consumes power. Other background services (often called daemons) can also consume power. Mostly these are pretty efficient, but for power users, it’s worth checking.
See my article “MacBook Air Battery Life” for more info on reducing power usage and making your Mac cooler and quieter.
Cause #3: Adobe Flash Consistently Using the Processor
Flash is software that can be installed as a plugin to most web browsers, such as Safari, FireFox & Opera. Google’s Chrome browser includes Flash. Flash is mainly used to include animated and video ads in web pages, to deliver web video and provide games in webpages. Flash is not uncommon for charting. It’s also often used for entires sites for big product launches, like Hollywood movies.
Flash tends to use a lot of CPU. Most people who use Flash aren’t professional programmers, they’re usually creatives. One poorly written banner ad can swallow an entire core of your MacBook Air’s processor.
While the latest versions of Flash do some hardware acceleration for video playback, Flash still uses considerably more CPU to play video than native video players like Quicktime X.
Consider if a Flash banner ads is not visible: it’s in other browser tab, your web browser is in the background while you’re in another app (e.g. Word), or the banner is in part of the webpage that isn’t showing in the browser window. The Flash portions of webpages continue to run and consume your processor and battery even when you can’t see them.
Flash’s heavy use of CPU was running of the reasons Apple doesn’t include Flash on the iPhone or iPad, and why Flash doesn’t come preinstalled on the MacBook Air.
To minimize Flash’s grip on your processor, you have a few alternatives:
- Use one browser window at a time. Quit your browser when you’re not using it.
- Use the free software ClickToPlugin for Safari. It stops Flash automatically running; it requires you the click a Flash part of a webpage to make it run – which sometimes you do (e.g. a YouTube video).
- Deinstall Flash.
- Deinstall Flash. Use Safari without Flash. When you really need Flash, use Google Chrome instead of Safari. Chrome includes Flash built in.
- Use FlashFrozen ($0.99) to automatically stop Flash running in the background.
Some of these techniques can be combined. For example ClickToPlugin plus FlashFrozen.
If you watch video on websites that also have animated ads beside the video (instead of in the video), you’re getting the double penalty of Flash video plus Flash ads at the same time. ClickToPlugin might be a good option here. You can just click on the main video to enable it, and leave the ads disabled, giving you the best chance of the MacBook Air staying cool and quiet.
See “MacBook Air Battery Life 2011” for more background.
Flash seems to be the most common cause of the MacBook Air overheating and fan running fast.
Cause #4: Software Incompatible with Lion
Some software doesn’t work with Lion. If it contains software that runs in the background and restarts automatically, the software can start over and over again.
I’ve seen one case of this, when someone migrated five years of accumulated software from their old Mac to their new MacBook Air using Apple Migration Assistant. The person was very technical and fixed the broken software themselves. This may have been old HP printing software, but I haven’t confirmed this.
For the technically inclined, there wasn’t much CPU usage, but with the process continually respawning the was a high run queue for the CPU.
I’ve seen serveral cases where people an overheating MacBook Air and noisy fans ran the free Onyx utility and that fixed performance issues. Write a comment if you’d like more specifics. In none of these cases has anyone reported the root cause of the problem, but for now I’ll include these cases here.
Cause #5: System Management Confused / Needs Reset
Thanks so much to Chris posting a comment about this:
I was experiencing a similar problem on my new MBA 13″ with i7 (loud fan with nothing running), along with some other odd issues related to battery and power. System preferences (energy saver) claimed my battery was charged at 0% (though I knew that was not the case), and I couldn’t add the battery status to the menu bar (I would click that option, the menubar with reconfigure as if to accommodate the new icon, but then it would disappear). Furthermore, when plugged in to AC, I got no lights (green or orange) on the MagSafe adapter. The support page at http://support.apple.com/kb/ht3964 suggested that weird battery/power issues may be solved by an SMC reset, which I did. The fans have now stopped and the other symptoms that I mentioned have also gone away. Perhaps this can help with others.
So Chris’s MacBook Air symptoms were:
- Loud fan with no apps running.
- Battery showing 0% charged in Energy Saver in System Preferences.
- Can’t add battery status to the menu bar.
- Status LED on MagSafe power connector not lighting up when plugged in.
You may not have all these symptoms.
- Shutdown your MacBook Air (go to the Apple menu and choose “Shut Down…”).
- Make sure your MacBook Air has external power. Connect the power adaptor, if it isn’t already.
- Using the Air’s built-in keyboard (not a plug in keyboard or bluetooth keyboard), of the left hand side of the keyboard press Control-Shift-Option and on the top right of the keyboard, the power key at the same time.
- Release all the keys at the same time.
- Press the power key to start the computer.
If this fixes your issue, consider replying to Chris’s comment below with a thank you for him.
MacBook Air Fan Noise and Heat Issues Fixed?
Did this help fix your MacBook Air fan running too fast / being too loud, of being very hot? Drop me a comment and let me know what you did, and how it worked for you. Your comment, like Chris’s, may really help others, as we’re still learning which are the most common causes, and what are the best solutions.
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