Earlier this year, I wrote several guides to boost the speeds of older Macs by swapping their internal hard drives for super-fast solid state drives (SSDs). As readers have confirmed, their older iMacs, MacBooks, and Mac Pros have seen dramatic improvements with new SSDs. But some people were left with a question: what should I do with my Mac’s old hard drive? Throw it away?

A great answer: put it in an external hard drive enclosure and keep using it! My latest How-To shows you how easy it is to reclaim your Mac’s old drive by installing it in a nice USB enclosure such as Akitio’s SK-3501U3 (shown here), which I chose because of its Mac-matching design, reasonable sub-$40 price, and compatibility. External enclosures are also ideal options if you want to choose a high-quality hard drive mechanism for yourself, rather than taking a risk on whatever might be hidden inside a fully-assembled external drive. I’ll explain that, and much more, below…

A Quick Primer On Internal Hard Drives

The vast majority of Macs in homes have mechanical hard drives (rather than chip-based SSDs) inside. Without a computer or another enclosure surrounding them, these hard drives are called “internal hard drives.” They’re small metal boxes akin to old-fashioned record players, with one or more spinning disks (“platters”) that get accessed by a “read/write head” (shown above). Hard drives aren’t all created equal, and they aren’t built to last forever: good drives typically last for around three years of very active use, and great ones for five years. Light use extends their lives.

With over 27,000 drives on hand, Backblaze last year published the most comprehensive independent test results I’ve seen for consumer-grade hard drives. Comparing Seagate, Hitachi GST, and Western Digital disks of various capacities, Backblaze found that Hitachi GST’s drives had the lowest failure rate at any capacity, followed closely by Western Digital, with Seagate ranking a very distant third. “If the price were right,” Backblaze said, “we would be buying nothing but Hitachi drives.”

But nothing’s set in stone: Western Digital now owns Hitachi GST, and Seagate has been working to improve the reliability of its drives. This year, Backblaze updated its findings with new failure statistics, noting that it now has over 41,000 drives in use. It found that Seagate’s latest 4TB drives are much better than ones it previously tested — still about twice as failure-prone than Hitachi GST drives, but not 20 times worse (like Seagate’s 3TB drives). Western Digital and Hitachi GST drives otherwise remained excellent.

In short, if you’re pulling a hard drive out of a three- to five-year-old Mac that’s been left powered on for most of its life, you might be better off disposing of it rather than continuing to use it until it fails. But a $40 external enclosure can keep your old drive going as a “just in case” backup, or let you choose the specific brand new internal drive you want from a great manufacturer. Why would you do that? Because if you’re thinking of buying a fully-assembled external drive, you may not know who makes the drive mechanism inside, which can be risky. Here are links to Seagate’s, Hitachi GST’s, and Western Digital’s internal drives, all of which are available in multiple capacities and price points. Just remember, the statistics demonstrate conclusively that cheaper isn’t necessarily better here.

Understanding External Enclosures

When you buy any fully-assembled external hard drive for your Mac, you’re really buying two things: an internal hard drive like the ones shown above, and an external enclosure. To keep costs low, the cheapest external enclosures ($15-$20) often cut corners by using bare-bones chips, cables, and materials. They also may not include power supplies, which means they’re fully dependent on your Mac for power. Buyers consequently sometimes complain about random disconnections, refusals to mount, a lack of Mac compatibility, or other problems.

The Akitio SK-3501U3 enclosure shown here is a very good option for the $35 price. It includes a USB 3.0 cable, a wall power supply, and the screws necessary to mount any 3.5″ hard disk inside. Akitio also sells a 2.5″ enclosure that’s physically smaller and designed solely for laptop drives. (If you instead want to use the SK-3501U3 with an adapter for a smaller 2.5″ laptop drive, the Newer Technology AdaptaDrive Converter is the one I recommend. It’s not needed for 3.5″ drives.)

Akitio’s enclosure is made from thick, solid-feeling aluminum that looks great next to a Mac. As you can see above, it’s a little smaller than the superb G-Tech G-Drive USB I’ve previously reviewed and loved, and its blue data indicator light is off to the back rather than glowing through the mesh front. The light only goes on when it’s connected to a computer and in use. There’s also a bottom-mounted heat sink to keep temperatures down, a design element found on older and larger G-Drives.

Full assembly requires around 15 minutes, one type 0 or sharp type 1 Philips head screwdriver, and zero prior experience. First, four small (and easy to misplace) screws get removed from the enclosure’s bottom, enabling you to slide the hard drive tray out from its center. You flip the tray over, attach four slightly larger screws to the tray and your hard drive, then slide the tray back into the enclosure. After replacing the four bottom screws, you apply four frosted clear rubber feet on top of them. That’s it.

The result is a completely functioning hard drive that’s plenty fast, with modern USB 3.0 connectivity that’s backwards compatible with USB 2.0 computers. Though speeds will vary based on the speed of the internal hard drive you place inside, the Akitio enclosure achieved Blackmagic Disk Speed Test results of 125-127MB/second when my old iMac’s four-year-old Western Digital drive was inside, and a USB 3.0 Mac was connected. That’s nearly as fast as the best speeds I’ve seen with the brand new G-Drive USB I purchased last December.

If your old hard drive will only be needed temporarily, you can consider an external hard drive docking station instead. Unlike enclosures, which are designed to completely cover, protect, and in many cases muffle the sound of the hard drive inside, a docking station such as the $40 Sabrent USB 3.0 dual-dock (shown below) or $23 single dock version can be used briefly to plug in 2.5″ or 3.5″ drives like pieces of bread in a toaster. There are no screws to mess with here; these are completely plug and play solutions. While I wouldn’t recommend them for extended use due to dust and noise considerations, docking stations can be viable alternatives for one-off access to drives you won’t keep using for long periods of time.

On the “easy to difficult” scale, putting your old internal hard drive into either an external hard drive enclosure or docking station is ultra-easy — almost certainly simpler than removing the drive from your Mac. It’s also extremely cost-effective, and there are many times when I’ve benefitted from having an external enclosure around to deal with an older, misbehaving hard drive. Having a 3.5″-sized enclosure with the option of using a 2.5″ adapter strikes me as the right combination for Mac owners with both desktop and laptop hard drives, but laptop owners with 2.5″ drives will be fine with smaller enclosures, and docking stations may work for some people. You can choose the solution that’s best for your personal needs.

Even More Great Options

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