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  1. Computer Skills
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Computers

Keeping Your Cool With Apple Mac Operating Temperatures

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Apple’s Mac range of computers are, literally, the hot technology of the day with shipments of some 13.5 million portable MacBooks Pro and 4.65 million Mac minis and iMacs in the most recent quarter. Compare this with the longest decline in PC sales history and you can see what I mean.

But Mac’s are physically hot, too, sometimes. If this is something about which you are be concerned then this tutorial will explain a little more about the causes, the problems and the solutions to your hot Apple.


Which Macs Are Affected by Heat?

Potentially, all of them. Whether you use an iMac, a MacBook Pro, a Mac mini or a Mac Pro, all of these machines are susceptible to heat.

The reasons for their susceptibility, in the first instance, may differ. It may be the design of the machine, where it is used or how it is used that contributes to heat-related problems.


What Problems Can Heat Cause My Mac?

It’s normal for Macs to generate some heat during use, but prolonged heat – or regular warming up and cooling down with the machine being turned on and off – is unlikely to do it any good.

It seems to be that some components do not deal with excessive heat well at all, particularly the graphics cards. A graphics card that is susceptible to heat, and failing, will sometimes manifest itself in scrambling the video output to the display.

Scrambled Display
Excessive heat can cause the video card to produce a scrambled display.

It has been suggested that heat is a cause of optical disc drive and hard disc drive failures, though this would be over the medium to longer term and is not necessarily conclusive.

The more likely issues that you will face will be slow performance and automatic shut downs, of your Mac, as it protects itself from becoming catastrophically hot.


Why Does My Mac Get So Hot?

These are some of the causes of heat build-up in Macs.

It’s Normal

Like any electrical appliance, your Mac gets warm – or hot – when it is in use. The nature of computers, and the components of which they are made up, is such that some of that electrical energy gets dissipated as heat.

Much of the heat that comes from your Mac is a result of components such as:

  • the hard disc drive, HDD, as it is a mechanical device powered by a motor.
  • the central processing unit, CPU, or just plain “processor” (Intel processers consume lots of energy compared to ARM chips, say)
  • the graphics processing unit, GPU, or “graphics card”
  • The display - the brighter it is the hotter it gets
  • Heat sinks - metal components designed to draw heat away

Rogue Apps

Rogue, or runaway, apps can put addition load on the processor and/or graphics card that can affect your Mac in a number of ways.

They may require more battery power, in the case of portable Macs, because the CPU/GPU is having to do more work. Processors doing more work create more heat and can lead to a degradation in system performance.

Design

Apple designs it’s Macs to dissipate heat using different techniques such as the use of heat sinks and/or fans.

iMacs, for instance, use fans to draw cool air up through the bottom of the aluminium chassis and across the components to expel the hot air through a thin, horizontal vent that runs almost the full length of the upper, rear panel.

Similarly, the original shape Macs mini draw air from around the base of the machine and expel hot air through the rear.

Not all Macs have operated like this. The G4 Cube employed a fan-less design that relied upon a convection based approach to cooling using the principle that hot air rises. The advantage of this was that it operated silently; the disadvantage was that it didn’t operate at all when it got too hot. That vent on top was there for a reason and should not be covered!

It remains to be seen if Apple has learnt from this; but it is looking likely that they have. The forthcoming Mac Pro is a tiny machine that houses powerful components in a small space.

Apple has built these components around, what they call, a “unified thermal core” which is a single piece of extruded aluminium. This core, running from bottom to top through the middle of the machine, is designed to maximise airflow as well as thermal capacity in drawing heat away from the components. A single fan draws air up through the computer to, as efficiently as possible, expel the hot air through the top.

Mac Pro thermal core
The forthcoming Mac Pro is built around a central thermal core to extract heat from components.

Tip: Aluminium is up there with gold, silver and copper as being a good conductor of heat!

Dust, Fluff, Crumbs, Lint

Let’s just call it dust. If you’ve ever opened a Mac that is more than a few months old, you might be shocked at just how much of that light-grey ‘stuff’ is trapped inside.

Over time, the build up of dust will reduce the efficiency of the cooling effect of the fans as less air will be drawn through which, in turn, directly means less cooling.

Depending upon your competence and confidence, it is possible to open some MacBooks Pro, Mac minis and iMacs. If you get the chance, it is a worthwhile exercise to clear out this build up of fluff. Use a can of compressed air to get it all out ensuring that you are in a largish area that can be easily cleaned. There’s no point just blowing lots of dust around your office!

Dust inside a Mac mini
This Mac mini has drawn in a lot of dust which will reduce the cooling efficiency of the fan.

Lack of Ventilation

It’s the gradual build up of dust and lint that causes a lack of ventilation, but you may have immediate ventilation issues depending upon the way that you use your Mac.

If you use a MacBook Pro, for instance, you may be used to working in different places, one of which might be on your lap in the coffee shop or on the couch. After all, it’s a laptop, isn’t it?

The problem with operating a MacBook Pro (or any laptop computer for that matter) on your lap or, worse still, on a cushion, is that you will be blocking the ventilation grills on the underside of the machine. The fans will work to draw air in but, instead, will pull in lint from the cushion or your clothing.

What’s more, a hot MacBook on your lap is not a comfortable proposition.

Tip: Place your MacBook Pro on a stand to facilitate plenty of air circulation around and underneath the machine itself.

Storage in Confined Spaces

Perhaps not normally a problem with MacBooks Pro nor iMacs, this could affect Mac minis. It’s a diminutive machine capable of being stacked on or under things on your desk. Perhaps it’s employed as a media centre and is safely stowed away in a cabinet of some sort?

The fact is, your Mac mini draws in air through the base and to operate effectively it requires space for adequate air circulation under and around the computer itself.

For all other Macs, ensure that there is sufficient space around them for adequate airflow.

Storage in Confined Spaces
There is not enough room around this Mac mini to provide adequate ventilation. What's more, it's inside a cupboard.

Direct Sunlight and Poorly Ventilated Rooms

The best advice is to never operate a computer in direct sunlight. You’re fighting a losing battle in trying to dissipate heat from an aluminium (good conductor of heat, remember?) machine that is subject to the warming effects of solar radiation.

The same goes for rooms that are hot or poorly ventilated. For example, in the summer my loft room gets quite hot. It is necessary to get ventilation by opening the Velux at the front and the windows at the back.

Screen Brightness

Brighter screens require more power to produce more light. The energy used by the backlights is dissipated not only in light but in heat, too.

Sometimes it is worth just turning the brightness down a little. Do you really need that retina-singeing image? Brightness is quickly adjusted using the F1 and F2 keys to make it dimmer and brighter, respectively.

Screen Brightness
Do you really need your screen on maximum brightness?

Tip: If the F1 and F2 keys don’t work as expected, press the Fn key simultaneously as the the default behaviour of the keys may have been modified.

Processor Intensive Tasks

Some applications require more processing power which, in turn, requires more energy and more heat.

If you work with video, photo or graphics applications, in particular, you will be familiar with this. Adobe Flash is another program that requires processing power. Much video content on the internet, such as on YouTube, uses Flash video.

It’s not just the CPU but the GPU, too, especially if you are placing extra demands on your Mac by having the GPU drive an external display.

Tip: Change your default browser video, in YouTube, from YouTube Flash video to HTML5 video


Monitoring Temperatures

Whether you are just curious or trying to troubleshoot issues that may heat-related, an excellent piece of software for monitoring your Mac is the Temperature Monitor app, from Marcel Bresink.

Temperature Monitor will give you live temperature information for many components in your Mac. It is particularly useful for logging a history of temperatures over a period of time. Ideal if you are troubleshooting as you can see how temperatures might be affected when you use different apps, for example.

Temperature Monitor
Monitor temperatures, of key components, over a time period.
The spike in the display reading (purple) was caused by turning the display to maximum brightness.

Another useful app for monitoring temperatures, and allowing the export of data to csv files, is Temperature Gauge from Tunabelly Software.

Temperature Gauge app
Temperature Gauge app is useful software for monitoring temperatures inside your Mac.

Overheating Solutions

If your Mac is running hotter than you expect, there are a number of measures that you can take to cool it down.

Don’t Use Your Mac in Direct Sunlight

Yes, it looks cool to sit outside and work on your MacBook, and it’s the lifestyle we’ve been promised with remote-working, but can you actually see the screen in the sunlight?

You’re getting hot. Your Mac is getting hot. Move into the shade, and ensure that any Macs located indoors are in the shade, too.

Use an External Fan

Obvious, really. Using a desk fan is an easy way of getting some air circulating. It doesn’t just keep you cool, it helps to propel hot air away from your Mac.

Air Conditioning

The converse to sitting in the sun, working in an air conditioned office means a lower ambient temperature which means that your Mac is not soaking up lots of external or ambient heat.

Ventilation

This isn’t just about opening windows or using a desk fan. It’s about ensuring that there is adequate space around your Mac to ensure that air is able to flow freely. Clear your desk!

Raise Your MacBook

Using a MacBook to drive an external display whilst using processor intensive apps, such as video or photo editing, makes for a very warm MacBook.

Consider investing in a stand to raise your MacBook above the desk so that there is plenty of air flow beneath it. Some stands come with low-noise integral fans to ensure that air is being moved on the base of your MacBook.

Using a stand to raise your MacBook Pro
Using a stand to raise your MacBook Pro

Open Your Mac and Clean Out the Dust

This is an easier task on some Macs than it is on others. I’d readily do this on a MacBook Pro or a Mac mini, but I’d hesitate when it comes to iMacs. Indeed, the way that Apple is going, it is becoming less easy to open Macs.

If you do open an iMac, use a can of compressed air to blow the dust out of the fans and out of the components. Don’t do this in your office, though, as the dust goes everywhere!

Tip: Do not attempt to open any Mac unless you know what you are doing. You need to be confident and competent. If in doubt, take your Mac to Apple or to an Apple specialist.

Software

If, having employed the earlier techniques, you are still concerned about the temperature of your Mac, you could give it a little help by running the fans a little faster.

This is done with a small app, SMC fan control, that allows you to manually adjust the minimum speed of the fans – from the default minimum of around 940rpm to 3,800rpm.

Of course, running the fans faster introduces more noise and there is an argument to say that running the fans faster will lead to them wearing out sooner.

Regardless, the benefit of using this software is going to be hindered to the point of uselessness if your Mac is stuffed full of dust or you haven’t followed the advice above.

SMC Fan Control
SMC Fan Control is a small menubar app that allows you to adjust the speed of the fans.

Cool Down, Chill Out

In this tutorial, I have examined why your Mac gets hot, what’s normal, what problems excessive heat may cause and what can be done to cool down your Mac. If you have had any heat-related issues with your Mac, or you have inventive ways of keeping your cool, please let us know in the comments, below.

And now that you've learned to cool down your Mac, why not explore what else it can do by checking out the useful Mac apps on Envato Market?

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