You can certainly take the drives out of old machines and use them as external drives on other systems. It’s actually a common and fairly easy way to perform some data recovery. As long as those drives aren’t the cause of the system failure in the first place, the data on them should still be accessible.
There’s a catch for running software from those drives, however, that I’ll speak to in a moment.
More to the point is getting the right external enclosure. Not only do you have size to worry about, but interface as well.
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Physical Drive Sizes
You’re most likely to encounter one of two different sizes of hard drives, 3.5 or 2 inch:
The larger drives are what you’ll typically find inside desktop PCs, and the smaller is used in laptops and other portable devices.
Naturally, the external hard drive enclosure that you plan to get needs to accommodate the size of drive you have.
Hard drives use one of two interfaces (connectors): IDE (Integrated Drive Electronics), sometimes also referred to as PATA (Parallel Advanced Technology Attachment), and SATA (Serial Advanced Technology Attachment). IDE/PATA is the most common on older computers, whereas SATA is prevalent in laptops and most new desktop computers.
External enclosures typically use one interface or the other – IDE/PATA or SATA. Make sure to get the enclosure that matches the drive that you’re planning on
putting in it.
The External Drive Enclosure
Besides providing a place to house the drive, an external drive enclosure typically does exactly two things:
- Provides power: When a drive is installed inside a computer, that computer provides the power to run the drive. That power is not typically available via external interfaces†, so most external drive enclosures include a separate power supply that is plugged into the wall or a power strip.
- Converts to USB: Most external drives use a USB interface. The minimal circuitry that’s included in an external drive enclosure is simply a conversion from USB to the internal interface of the drive. (Occasionally, external drives can also be connected by Firewire, also known as IEEE 1394. As this is more common in Macs, check to see if you need this interface. If so, make sure that your external enclosure uses this, often in addition to USB.)
Note the absence of any cooling. While a few external drive enclosures include fans, most do not. This can be an important consideration because hard drives can run hot. Without a fan of its own, the external drive enclosure is relying on ambient airflow to keep the drive cool. Make sure that it’s used in an open and unobstructed location.
Data On External Drives
For the most part, an external drive is just another hard disk on your system. While external drives are commonly used for backup, you can actually use it for almost anything that you might use an additional internal drive for.
- I don’t recommend installing software to an external drive. By that, I mean any program that uses a setup program. External drives may see their drive letters re-assigned occasionally. While annoying for any number of reasons, it’s particularly problematic if a program installed as being on the “G:” drive is suddenly on “H:”.
- In your case, because the drives used to be internal drives, software that was previously installed via some kind of setup will not work. That software will need to be set up again from original setup discs. On the other hand, portable applications that don’t require a setup will usually work.
- An external drive is likely to be slower than an internal drive. That means that, depending on how you’re using it, you may not want to put files on it that you access heavily; this includes program files.
- An external drive is, as far as the operating system is concerned, ephemeral. They can be removed at any time. The operating system shouldn’t allow you to place the paging file on an external drive, for example. (If it would allow it, don’t, for the speed reasons I just mentioned.) Similarly, I would not recommend moving My Documents, the system temporary folder, or any system-defined folders to an external drive. Should the external drive ever be removed, your system will be very, very confused.
I find that external drives are the perfect places to keep large quantities of accumulated data that I’m not constantly accessing. Backups, for example, as well as photos, videos, documents and more.