How and Why to Upgrade Your Mac’s Hard Drive

As a follow up to our article on upgrading your Mac’s RAM, this article will outline how to go through the same process to upgrade your hard drive.

We’ll begin with a brief discussion on why upgrading your hard drive will improve your system then move on to the pros and cons of mechanical vs. solid state drives. We’ll conclude with a step by step tutorial on finding and purchasing the right HD for your Mac and point you to some instructional guides outlining the installation process for your specific model.

A Tale of Two Variables

There are two primary reasons to upgrade your hard drive: storage and performance. The first one is simple to understand. If your hard drive is constantly filling up and forcing you to offload or delete files, then you probably need a bigger drive.

The second variable is much more complex and can, in fact, get quite techy. As we’ve learned, the performance of your Mac can largely be improved by upgrading your RAM. However, the hard drive also plays a major role in the speed of various activities such as data access and startup times.


A Mac Hard Drive

The primary factors related to the speed of your Mac’s hard drive are RPM and cache size. Rotations per minute (RPM) refers to how fast your hard drive is spinning and directly correlates to how fast it can read and write data. Though there are plenty of arguments out there regarding how easy it is to be deceived by a drive’s RPM, they are all supremely technical in nature and sound like a foreign language to anyone not familiar with terms like IOPS and partial stroking. For the purposes of this article, we’ll assume that more RPMs equals higher performance. For example, a 7,200 RPM hard drive will perform better than a 5,400 RPM drive.

The buffer cache refers to a temporary storage area that is used to enhance the drive’s performance. According to, “when the computer requests data from the hard disk if that data is in the cache, there is a performance boost directly related to the speed of the cache.” So generally speaking, the larger the buffer cache size, the better the performance of the drive.

Solid State Drives

The information above is relevant for typical hard drives, meaning those that actually spin. The basic idea is that a disc full of positively and negatively charged area spins under a read/write device called a head. As with anything containing moving parts, these devices are quite prone to failure. In fact, these precariously spinning objects have one of the highest rates of failure of any component on your machine. It’s unfortunate that the part likely to die on your Mac first is the part holding all of your valuable data.


A Mechanical Drive and a Solid State Drive

Solid state drives are a pricey alternative that contains zero moving parts and therefore a much lower chance of something going wrong with the device over time. As an added bonus, there is no initial start up time as there is no disk to get spinning. Furthermore, reading and seeking times can be in the hundreds of times faster with SSDs than mechanical disks (source).

The primary downside of SSDs is currently their price but there are also arguments regarding information recovery that can be perceived as either a pro or a con. Deleting files from a solid state drive leaves a lot less residual data which can make it difficult or impossible to recover lost information. On one hand, this makes these drives much less of a security threat to anyone concerned about thieves pilfering their drive for information. On the other hand, sometimes tragedy strikes and you actually want to be able to recover lost data and a drive that makes this impossible will not be pleasant to own in this circumstance.

Below we’ll look at both options when examining how to purchase a hard drive. We’ll go step by step through the process of how to discover which drive you need and where to find a replacement.

Step 1: Learn About Your Mac

As we did with your RAM, the very first thing you need to do in your hard drive upgrade process is to find out the technical information you’ll need to know to purchase the right hardware (this section will be a little redundant if you’ve already read the RAM article but is helpful to newcomers). To do this, click on the little Apple icon in the very top left of your screen and select “About This Mac” from the options. The following window should pop up.


About This Mac

As you can see, this handy little window tells you which version of OS X you’re running and provides info on your processor and memory (RAM). The picture above shows you that I have a 2.16 GHz Intel Core 2 Duo process with 3GB of RAM. Don’t worry in the slightest if none of these numbers make any sense to you, just jot down your processor information from this window (a quick screenshot would suffice as well). We’ll use this information later to determine which hard drive to buy.

After you’ve saved the information from the about window, hit the button that says “More Info.” This will take you into an application called “System Profiler” that contains all kinds of technical information about your Mac. As you can see below, down the left side there is a series of categories. Click on “Serial-SATA” under the “Hardware” heading (most newer Macs contain SATA drives, older models might contain IDE/ATA drives.).


About This Mac

Here you can see the current model, serial number and capacity of the drive currently in your system. As you can see in the screenshot above, I’ve got a 120GB drive with only about 20GB free. It’s about time for me to upgrade! As we stated above, RPMs are something we want to pay attention to and they are not represented in this information. The easiest way to find this out is to jump over to EveryMac.

Step 2: Find Your Mac on EveryMac

Again we’ll follow the same process as we did in the RAM article to locate the right Mac on This website features tons of useful information about every Mac in existence and is always my first stop on an upgrade quest.



Scroll down until you see a list of Macs separated by series, year, processor, etc. under the heading “Recent Apple Specs.” Now click on the Mac you own under the “Series” heading. For example, I clicked on “MacBook.”


Find Your Mac on the List of Models

Next you should see a list of the all different versions of your Mac that have ever been released. This is where your processor information from the Apple “About This Mac” screen will come into play. As you can see in the pic below, I found my 13″ 2.16 GHz Macbook and clicked the dropdown for a quick breakdown of my specs.


Click the Arrow to Open the Dropdown Menu

Next, click the link at the bottom of the dropdown for complete specs on your selected machine. This will take you to an entire page of information devoted to your specific model and version of Mac. Here you can read all kinds of interesting information about your Mac and what made it unique when it launched. Scroll down past all of this info to the section of the table labelled “Standard Hard Drive.”


Find Your Hard Drive's Specs

As you can see in the screenshot above, the standard hard drive in my model is a 120GB 5400 RPM drive. Armed with this information, let’s jump over to OWC to find a decent upgrade.

Step 3: Finding and Purchasing the Right Upgrade

Now that you have a general idea of what’s currently in your Mac, stop by Other World Computing to see if you can find something better. On the home page, click on the “Internal Storage” button in the navigation at the top. This should bring up the following screen.


OWC: Choose Your Category

As you can see, they make it really simple to choose the category of drive you’re looking for. In my case, I’m looking to upgrade my MacBook, so I’ll click on the laptop hard drive option. Choose the option that matches the specs you saw on everyMac and in your System Profiler window.


Select Your Drive

The top of this page informs me that the hard drives here will work on all 2006 and later models, including all MacBooks. This provides me with additional confidence that the drive I select will in fact work with my machine.

As you can see, I have the option to either go with a mechanical drive or a solid state drive. True to what we discussed earlier, the solid state drives are quite a bit more expensive than the mechanical drives so make you’re confident that you won’t be happy with a traditional drive before upgrading to an SSD.

The traditional drive options are actually quite affordable. I can upgrade my 120GB 5400 RPM 4MB cache drive to a 500GB 7500 RPM 16MB cache Hitachi drive for about $100. That should provide me with some significant performance upgrades and instantly solve my quickly depleting supply of available storage.

MacRumors Hard Drive Quick Reference

If you know what you’re doing and don’t want to go through all the steps above to find the replacement drive you need, I’d recommend taking a look at the quick chart of hard drives for various Mac models from Mac Rumors.

Other Places to Buy a Hard Drive

Always be sure to shop around to get the best deal. Many times, OWC will have the best price but there are definitely other options to check as well. Here are four other stops to make before you make a decision.


New Egg


Crucial (SSDs)


Mac Improve



Step 4: Installation

Every Mac model is different and will have its own unique process for finding and removing the hard drive. Before I’ve compiled a list of links to some instructional videos that will show you exactly how to replace your specific Mac’s drive. For complex tasks such as replacing a hard drive, I find video tutorials to be much more helpful than a static instructional guide as you can actually view the process as it’s happening and can therefore be confident that you are doing it right.



Mac Pro/G5


Don’t see your model? No problem, this is just a small sample of OWC’s super helpful instructional videos. You can view a full list here.


To sum up, upgrading your Mac’s hard drive will not only increase your available storage, but will also improve your machine’s performance.

Your two options for hard drives are mechanical and solid state. Traditional mechanical drives are far more affordable but suffer from wear and tear as time goes on and are therefore prone to failure. Solid state drives by contrast are an expensive alternative with faster startup and seek times. Though many believe that SSDs represent the future of hard drives, they can be pretty uneconomical at this point in time if you’re looking for a simple and affordable upgrade.

I hope this article has emboldened you to take on the intimidating task of upgrading your Mac’s HD if you’re in the market to do so. The videos above really break it down nicely and can make the entire process relatively easy if you have even the slightest bit of computer hardware experience.

Let us know in the comments below if you have any other basic hardware or software instructional guides you’d like us to put together. We’re eager to hear your ideas!