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How-To: Make your Mac run silent, cool and fast under OS X El Capitan


As expected, Apple’s release of OS X El Capitan for Macs was less about adding major new features than “refining the experience and improving performance” from Yosemite — in other words, under-the-hood optimizations to make any Mac run more reliably than before. Thanks to El Capitan, my older (mid-2011) 27″ iMac is running better than it has in years: fast, quiet, and cool enough that it might as well be fanless. Rarely does the volume level in my office climb above a whisper, an experience I’ve come to love so much that I’d never want to return to a loud computer.

“WAIT!,” you might be saying. “My Mac’s fan is on all the time. Apple didn’t start selling iMacs with silent solid state drives (SSDs) or hybrid Fusion Drives until late 2012. How could your older Mac be that quiet?”

Below, I’ll walk you through seven steps that will help you bring your older Mac to a hushed, zen-like state. The first four involve mostly free software, and the last three are small hardware upgrades…

The Big Picture

Think of your Mac as being like an aging refrigerator that’s constantly being opened and closed, primarily holding cold food in storage, while various cold items are being taken out, then replaced with hot food that needs to chill. At some point, the fridge will inevitably get overloaded and dirty; it’s possibly going to stop working perfectly, too. While you could go and buy a new fridge, that’s not necessary — if you optimize the way you’re using and managing the fridge’s space, you’ll be fine.

Part of the reason my Mac runs silent is the hardware — I’ve added a few things that make it more efficient than a stock 2011 iMac. But software is another big part of the story, so that’s where I’m starting.


1. Check Your Dock. Those little dots under the dock icons are there to indicate apps that are currently in use, and as a general statement, the more apps you have open at a time, the more things your Mac is juggling at once. Apple has added some automatic resource-saving features to OS X, such as freezing currently inactive Safari tabs, but it’s wise to free up as much of your Mac’s RAM and CPU processing power as possible. This is especially helpful if you have 8GB or less RAM, or a dual-core CPU. Close apps you’re not actively using, and within active apps, close windows (such as images in Photoshop, or documents in Preview) when you’re done with them. You’d be amazed at how much faster a Mac feels when a bunch of Photoshop windows have all been closed.

usersgroupselcap2. Disable Unneeded Login Items. Go to the Apple menu at the top left of your screen, choose System Preferences, then select Users & Groups. Under the Login Items tab, you’ll find a collection of apps — typically “helpers” — that the Mac automatically loads every time it restarts. Select any items you no longer actively use every day, hit the minus button, and they’ll disappear from the list. Your Mac will typically load a little faster, and save a little memory in the process.


The System Preferences window doesn’t show you all of the items that auto-load with your Mac. You can get a better sense of how many “helpers” are hanging out by looking at the top right of your screen, though the icon list will also include Apple’s OS X icons for Time Machine, Bluetooth, Wi-Fi, Volume, Spotlight, and Notification Center; it may also include icons for currently active apps (such as Tweetbot, shown) which don’t have helpers. Adobe is one of the companies that keeps secondary apps running in the background to verify licenses and offer updates; you’ll typically have to fully uninstall the original apps in question to get the “helpers” off your Mac.


3. Watch Activity Monitor. While this type of digging qualifies as “going down the rabbit hole” in my experience — likely to lead to a lot of (mostly fruitless) Google searches — using Spotlight to load Activity Monitor (hidden in your Mac’s Applications > Utilities folder) can help you identify apps that are eating unreasonable amounts of CPU and RAM for whatever reason. Activity Monitor opens in the CPU tab (above left), organized by the percentage of your CPU’s capacity each app or background process is using. Alternately, you can click on the Memory tab (above right), which shows how much of your Mac’s RAM is being consumed by various apps and background processes. Click on the Memory header to sort the processes by memory footprint.


I called this a “rabbit hole” because many of the “activities” found here are unidentifiable based on name alone, and likely to lead to initial confusion. For instance, “WindowServer,” “kernel_task,” and “mds” are all required OS X processes, and likely to be in your top 10 memory eaters, possibly also CPU eaters, but they need to be there. There are dozens of processes competing for your Mac’s attention, so if you’re going to hunt around here, focus mostly on ones that are using a lot of CPU time and/or RAM. Photoshop, for instance, was consuming around 2.5GB of my iMac’s RAM without any windows open, a sign that closing it could free up a bunch of memory and improve performance. The RAM-hogging apps on your Mac will likely differ.


4. Clear Out Hard Drive Cruft (Make Space). I’ve written a detailed article on the topic of how to clean and speed up your Mac using the free apps GrandPerspective and OnyX, so I’m not going to repeat everything here. But one of the things that begins to make Macs feel like they’re failing is “overstuffed refrigerator” syndrome. GrandPerspective lets you visualize your Mac’s hard drive as a collection of colored boxes. DaisyDisk ($10, above), chosen by Apple as a Mac App Store “essential,” provides a cleaner and more interactive circular interface for doing the same thing. By hovering over colored bars, you can see exactly what folders and files are filling your drive, then delete (or manage) ones that have become unruly. 

I’ve found that my Macs generally need around 50GB of truly free “work space” to avoid slow downs and “running out of space” OS X notifications. If OS X doesn’t have enough space, it will struggle to work within whatever’s there, slowing down and possibly doing an excessive amount of back-and-forth writing to your drive. I like to have 100GB of empty space on my Mac, but if you’re using a small, space-constrained hard drive, you may not be able to do that.

5. Replace Your Mechanical Hard Drive With A New SSD. Readers have emailed me to tell me how much they loved my advice on replacing their old Mac hard drives with new solid-state drives. (Here are links to my guides to iMac HD-to-SSD swaps, MacBook/Mac mini/Mac Pro HD-to-SSD swaps, and iMac/Mac mini/Mac Pro CD/DVD-to-SSD swaps.)

As I’ve said before, this is the absolute best upgrade I’ve ever made to a Mac: putting a 1TB Samsung 850 EVO into my iMac radically improved its speed for doing everything, and made the machine whisper quiet. After getting the parts and spending around 30 minutes doing the installation myself, my iMac was getting 5 times faster disk speeds (a huge improvement, on par with far newer Macs), and many months later, I can use one hand to count the number of times I’ve heard the Mac’s fan turn on. It’s amazing. Read the guide above for your Mac model and take the plunge — you’ll love it.


6. Consider Offloading “Only As-Needed” Files Onto An External Drive. Going back to the fridge analogy, there are situations where you actually need more than one refrigerator — the one you keep in your kitchen, and either a smaller spare elsewhere in your house, or a big freezer in your basement to store oversized items. External drives are ideal ways to hold giant movies, music, or photo collections that just don’t need to be accessible on your Mac all the time.

Regardless of the size you choose, I strongly recommend G-Technology’s G-Drive USB (reviewed here) as the best overall balance of reliability, performance, and quality I’ve found in any traditional hard drive. It’s not the cheapest drive out there, but it’s the one I trust with my most important (but not daily-used) files, enabling me to keep plenty of free space on my Mac’s internal disk. My guide to choosing the best Mac external hard drive explores other options, including portable drives and SSDs.


7. Add RAM. While swapping out the hard drive made a huge difference in my iMac’s speed and ability to operate silently, adding RAM will be a real performance booster for a lot of people — assuming your Mac has user-replaceable RAM, that is. RAM is your Mac’s primary “work space” for juggling content from multiple apps; when it runs out of (very fast) RAM, it will try to find (slower) free hard drive space to use temporarily for the same purpose, and crawl to a halt if it can’t find enough. Having more RAM instantly addresses the software-related issues mentioned in 1, 2, and 3 above — the more RAM you have, the less often you’ll need to worry about closing apps or windows to keep your Mac running at full speed.

My guide to easy RAM upgrades for Macs will lead you through choosing the correct RAM for your machine, including model-specific guidance for Apple’s MacBooks, MacBook Pros, MacBook Airs, iMacs, Mac minis, and Mac Pros. Older Macs are typically very easy to upgrade with RAM, using little more than a screwdriver for installation, though many newer Macs no longer allow RAM upgrades. Since some Macs currently running El Capitan shipped with as little as 4GB of RAM, they can be upgraded to 8GB for markedly better performance. But I’d strongly advise upgrading to 12GB or 16GB if your Mac is capable of doing so; it will make a very real difference when running multiple apps, helping your Mac to run as fast as possible without tapping your hard drive for extra space. My Mac RAM upgrade guide will help you figure out how much RAM your Mac is capable of using.

More From This Author

Check out more of my editorials, How-To guides, and reviews for 9to5Mac here! I’ve covered a lot of different topics of interest to Mac, iPad, iPhone, iPod, Apple TV, and Apple Watch users. I’ve recently discussed how to safely prepare and wipe your iPhone for resale or trade-in, and how to get the best iPhone trade-in price to help buy an iPhone 6s, amongst many other topics.

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  1. Seth Weintraub - 8 years ago

    Honestly, now that the weather is getting cooler, I am going to run some processes in the background to keep my Mac Pro heating the room. Magic!

  2. PhilBoogie - 8 years ago

    1) The dots in my Dock are black. But that’s obviously I’m using it “Rhapsody Style”.

    2) I’d advice strongly against making your default account an Admin one. Use a separate account for that; the moment OSX asks for Admin rights you’ll simply get a popup requesting credentials.

    3) If I were you I’d first work through those 3,700 mails awaiting your attention¡

    4) Seriously, good article Jeremy!

    • Jeremy Horwitz - 8 years ago

      On point 3 – I’ve said it in prior articles whenever someone points out the number of emails, but I get a lot of unwanted mail (mostly story pitches) every day, and I’m not an inbox zero person, acknowledging every one of them. There’s not enough time in the day to manage all that and also test things, write articles, etc.

    • What worked for you?

  3. Will Van Gelderen - 8 years ago

    I’ve always wondered, is it normal on Macs that once used ram reaches close to 100% the system fan speeds up. I know free ram is wasted ram, but if it keeps my mac quieter and cooler then I would assume thats good

    • Jeremy Horwitz - 8 years ago

      Honestly, free RAM isn’t wasted RAM… it’s a buffer against slowdowns. Back to the fridge analogy, if you stuffed every cubic inch of your fridge with food, it would be a hassle to access certain items, and really impact the cooling ability of the hardware, as well. On a Mac with no free RAM, the fan will likely kick in because the CPU and hard drive become engaged in managing overflow from the memory. It’s best to have memory to spare.

      • myke2241 - 8 years ago

        it is said that a full fridge is more efficient because once the items are cool they keep the temp more stable and thus requiring less energy to cool down new items. that makes me hungry!

      • Jeremy Horwitz - 8 years ago

        I guess it depends on how you measure efficiency. If you’re talking solely about being able to maintain a constant temperature, sure. But if you’re frequently moving things in and out, you’re going to waste a lot of time juggling items in and out of very specific (and sometimes hard-to-reach) spaces. The challenge of ‘moving small bits around in a large, jammed environment’ issue is why, in the absence of streamlining the existing environment, adding extra space is an easy fix.

    • lepolero - 8 years ago

      thats RAM compression introduced in Yosemite, its consumes CPU power for the RAM to compress, its more noticeable if you fill up your memory fast (like starting up virtual machine in Parallels or opening a big Photoshop file). its fine feature when you occasionally use memory heavy apps, because (that depends on whats in the memory, some things compress well, some not even a bit) you can have “10GB of usable memory”, and have only 8GB physically in your Mac (thats really really simplified, so dont kill me for it). If you fill up your memory slowly, you will not reach that critical situation with 100% CPU load, since its compressing on the fly.

  4. Will Cate - 8 years ago

    I’ve also noticed that El Capitan handles the presence of numerous external drives more gracefully — i.e. Open File and Save File dialog boxes do not take nearly as long to draw (waiting for ext. drives to spin up). I like that a lot.

  5. I added RAM recently, 16GB total. Now, OSX only is using about 10GB just because it’s available. Bad memory managing.

    • Jeremy Horwitz - 8 years ago

      That’s really bizarre. I have 12GB in my Mac, and even with 15 open apps (not including OS X), only 8.8GB of memory is being used. Can’t imagine how or why OS X would be using 10GB on your machine.

    • standardpull - 8 years ago

      Don’t think that Mac OS X won’t use all available hardware resources for improved performance.

      Having the OS use RAM for caching disk in otherwise idle RAM is one of the most powerful IO performance techniques out there.

      It’s faster than every SSD on the market by way more than an order of magnitude.

  6. seanadb - 8 years ago

    Jeremy, what year is/was the Mac you upgraded to the 1TB SSD?

    • Jeremy Horwitz - 8 years ago

      It’s a mid-2011 27″ iMac. Runs incredibly well.

      • seanadb - 8 years ago

        Nice. I have a spare 2009 24″ iMac, still debating whether to put a SSD into it to improve speed. I should just dive into it and get it over with. : )

      • theronster - 8 years ago

        Do it. It’ll make a huge difference. I do about 4 or 5 HDD to SSD drive upgrades a week and every single one is a dramatic improvement.

      • Peter Hillman - 8 years ago

        My iMac 27″ Mid-2011 also runs incredibly well with a Samsung 1TB 840 EVO SSD. I installed mine behind the optical drive using the second internal SATA connector, leaving the stock 1TB HDD installed as a secondary drive. The SSD is now the primary drive and it is really fast. I also did the same Samsung 1TB 840 EVO SSD upgrade with my late 2011 MacBook Pro 15″. I won’t buy another Mac with a standard or fusion drive. I will buy it with 1TB of flash memory for the best performance.

  7. Ken Humphlett - 8 years ago

    When I updated my Late 2011 13″ MacBook Pro to El Capitan, not only did the my fan run all the time but it was burning hot. I used an app called Temperature Gauge and it was over the boiling point. With a web search I found out an article about looking for what process was using the most CPU. CalendarAgent was using 160% of my CPU. I found another article that talked about Google calendar sync causing this. I removed the google accounts. The CPU temps lowered immediately and fans finally stopped running. I waited a while and added the accounts back and the the temperature spikes didn’t come back.

  8. Oflife - 8 years ago

    The only task that gets my 2015 MacBook Pro Retina i5 512GB SSD 8GB RAM fans spinning is Chrome, when the Flash plugin is activated. Else, it handles most things without any problem.

    • Estefan (@smartone194) - 8 years ago

      Same for me!! Exact same specs just mine is a mid-’13 laptop. Any suggestions?

      • Marco Mul - 8 years ago

        I upgraded my MacBook Pro early 2011 this weekend with a Samsung 850 Pro 512GB. I followed one of the many online guides that talk about Carboncopy to copy your configuration on your HHD to your new drive and then you just have to swap them.

        After I did this, I noticed that the fan started to blow for anything that I started. Just opening a webpage was enough. I cleaned the fan and indeed found a bunch of dust collected behind the exhaust of the fan. That must be it, I thought. But after starting my computer, it started the fan again quite soon.

        Then I restarted my macbook via the old HDD on usb. Silence as I was used to before.. no fan going nuts on anything I started. So I created a bootable USB stick for a clean install. I have not heard the fan ever since. Only in cases that are normal because it requests more of my MacBook.

  9. Helen Mosbrook - 8 years ago

    My 2009 iMac never makes a sound until I turn on iTunes. Am I doing something wrong?

  10. i have an MBPr with 16GB ram , 1TB flash storage and i’m working with a secondary monitor on the thunderbolt/minidisplay-port .. especially since 10.11 my fans are going nuts .. even with the slightest bit of system-use (for instance running ableton live without any plugins) the GPU is heating up to 75°C and the fans running permanently at 3500 rpm and more .. wich is quite noisy, especially in a small music-production studio
    the only thing that helps right now is closing the lid of the laptop – so the GPU has less work to do – as a result the GPU cools down to 50°C within 2 minutes and the fans are going down to 2000rpm and are close to be silent
    if i do some 3d rendering or FCP-X i cannot close the lid as the GPU runs very quickly over 80°C .. so when i’m doing some film cutting the fans are mainly between 4000-6000 rpm.. i hardly can work like this

    to sum up: i have an 3500€ professional laptop but if i use it with a secondary monitor (a basic requirement for professional work) it’s very annoying to work on it – on 10.10 it was a little better – at least when doing cpu/gpu easy things the fans kept quit

  11. Mike Power - 8 years ago

    What do you think about Sym Linking? I’ve moved several large folders and databases to an external HD to free up space on my rather small (128 GB) SSD. It has worked very well so far.

  12. richa ✌ (@heyreech) - 8 years ago

    I got the 250 GB Samsung 850 EVO SSD and installed it in my early 2011 Macbook Pro 4GB. The SSD completely crashed and I had to salvage what I could with an external HD and Recovery mode. Anyways long story short I send the SSD back to Samsung and they sent me a brand new one telling me to make sure i had TRIM enabled. Well I have El Capitan so I hoped that problem was solved. My MB is very loud lately. But I do have it connected to an external display. Could that be the issue? The fan always runs super loud when I’m watching most videos/shows. It doesn’t get hot or anything the fan just goes crazy, will calm down for a bit, and then back to being loud. Sometimes if I just shut the lid when the fan is running very fast my MB won’t go to sleep. I’m hoping this isn’t my SSD malfunctioning again because the fan started acting up before my MB crashed last time. My macbook itself is not lagging or getting too slow/ glitchy and that’s the only reason I haven’t started freaking out lol. But no worries back ups are locked and loaded. Anyone know what’s going on?

  13. James Rogers - 8 years ago

    Awesome article :)

    I ditched a perfectly good high end PC and got myself a Late 2009 iMac 2.15″ C2D (iMac10,1). It came with 12GB of RAM, which I’ve subsequently upgraded to 16GB (Crucial: 2x4GB + OWC: 2x4GB), at the correct speeds for the iMac.

    Since I got it (second hand obviously) I have found that it runs incredibly hot. Like 75degC. I installed Macs Fan Control and have set it to custom so it works within certain ranges. I have used external hard drives to prop up a laptop cooling pad against to the back, with the fan pointing away from the iMac, sucking air away from it. I’m wanting to get a much better solution than this though, maybe a three fan setup (it’s sitting in the top left of the iMac now, when looking at the iMac, as it was the hottest area).

    Also. I upgraded my Early (I think) 2011 MacBook Pro 15″ to 16GB RAM and 250GB Samsung EVO SSD in HDD bay and a 750GB drive in the ODD. Worked amazingly well. Was a serious kick in the butt for the MBPro (4yrs old at the time).
    Now that I have the iMac, I want to take out the 1TB and put it in a dock and put a 250GB SSD in it’s place. With such an old model, is this going to make any difference at all, given it’s SATA speed limitations? I don’t have the necessary tools for the upgrade and the local company I deal with that do, are refusing to do it saying that it might cause damage to the iMac and they don’t want to be held responsible. If I recall correctly, to get the tools and a Crucial 240GB from someone that can import for me, is going to cost about R2900 (South African Rand). This is a non-starter for me.
    Should I be dreaming of SSD in my iMac or do you think it’s too late for this lil guy and I should be content with what it can handle? What about a 2TB server grade SATA drive with masses of cache and (if it’s possible) 10000rpm drive speed. That’s probably going to cause a lot of heat :(

    At the moment, it really is hot to the touch. Any ideas on that?

  14. likota - 8 years ago

    This worked for me on MBP 2009 and only 4GB of RAM… simple and effective SMC ‘cleaning’: -your-mac/#gref

  15. Raymond DeMartini - 8 years ago

    Add an SSD to your older iMac or MacBook Pro and max out the RAM. Makes a world of difference and it’s not that expensive and easy to install.

  16. Julie Brown - 7 years ago

    One thing many forget is that everything on your desktop will load its icon before you are fully ‘UP’ If you have a desktop full of shortcuts and files it WILL take longer to boot. I suspect the OS checks the integrity of any shortcut also. For handy shortcuts, create a folder of your own (anywhere but the desktop), stick them all in there and add this to the dock. Now in one click of the dock all your shortcuts are available. Files, well just move them to a sub folder. I create 3 or 4 primary folders on the desktop for my ‘channels’ e.g. domestic, work, entertainment and then everything goes under these. A clean desktop – try it, you will like it.

  17. douglasgordon304 - 7 years ago

    Hi, thanks for sharing a brief list of Mac speedup tips. However, removing the junk files from the Mac hard drive is a time-consuming task and results in the accidental deletion of important files stored on the macOS hard drive. Therefore, I always try to use some professional Mac cleaner software like Stellar Speedup Mac App, which can do this without any loss of files.