How to Buy An Internal Hard Drive

  • Category: Buying Guides

By Matthew Murray

About the only time the average computer user is not concerned with running out of storage space is the first day a PC is being used. Start installing programs, copying over tons of backup archives, and filling folders with photos, music, and video, and all those initially voluminous gigabytes can melt away before your eyes. It may take a month, it may take a year, or it may take two, but no matter how much free storage you start out with, you're eventually going to need more. Remember the old axiom: Data always expands to fill available space.

Internal storage would seem like an easy thing to buy: Just find the biggest drive you can afford, and you're all set. Go shopping, however, and you'll rapidly discover just how overwhelming the process can be. Are multiple terabytes (TB) of storage space worth paying for? What should a hard drive's rotational speed be? For that matter, would you be better off with a solid-state drive (SSD)? And is one drive, of any kind, enough? This guide will help you wade through these and other questions that are standing in the way of the storage space you probably want and almost certainly need.

Remember, these guidelines are only for internal storage—the kind you'd use for permanently housing your operating system, programs, and data. If you're looking for an external drive, for extra-secure backup and for carrying around your files with you wherever you go, be sure to read "How to Buy an External Hard Drive." Stick here, and we think you'll find that shopping for stay-in-place hard drives really isn't hard at all.

How Much Space Do You Need?
When you're shopping for an internal storage drive, the most crucial characteristic is its size. This will affect every other choice you make and how much you pay—unsurprisingly, larger drives are usually (but not always) more expensive than drives with smaller capacities. If you regularly shoot videos or use your PC for recording television, go for the biggest hard drive you can get: upwards of 1TB, maybe even upwards of 2TB. Serious photographers who store lots of photos in RAW format will also want a fair amount of space, as will music lovers with vast MP3 or AAC libraries and serious gamers. (If all you play are casual games, you're probably fine.) Everyone else can probably get away with less; you don't need much space to just install Windows 7 and Microsoft Office, and store Word documents, Excel spreadsheets, and a small collection of family photos.

Note: Though current hard drives offer capacities up to 3TB, and larger drives still are reportedly in the works, some PC systems (particularly older ones, or those running Windows XP) may have trouble recognizing all the space on drives larger than about 2.19TB. A number of companies have developed workarounds for this: Western Digital includes a hardware-based host bus adapter (HBA) with drives like its 3TB Caviar Green, and motherboard manufacturer Asus and storage magnate Seagate have developed software applications that provide access to all that space under certain conditions. Just be prepared to need to do a (tiny) bit of extra work if you're desperate to own the biggest drives on the market. (For more insight into this issue, read "The Problem with Big Hard Drives.")

How Many Drives Should You Buy?
Though mainstream systems with only one hard drive are still the most common configuration you'll find, many manufacturers and power users have begun switching over to multiple-drive systems. There are some real-world benefits to having more than one drive installed on your computer. Chief among them are speed and value, which we'll get to later, and the security of knowing that neither a catastrophic Windows crash nor a freak power supply failure will hose a decade's worth of cherished memories or vital business records. Having one drive exclusively for your programs and at least one drive for everything else is about the best compromise possible. If you don't think you'll need all that space, a single, high-quality drive will be fine.

Hard Drives or SSDs?
Hard drives are no longer the objects of mystery and fascination they were in the 1980s— these days, they fulfill their role both efficiently and affordably. But they're no longer king of the speed hill: Because they're mechanical devices that operate by way of spinning platters and seeking heads, you're at the mercy of the physical hardware when it comes to reading or writing your data quickly. SSDs are another thing altogether: They're based on flash memory, which means that storing and extracting information occurs much faster, something you'll really see when you're opening and saving HD videos or even booting up your computer each morning.

Why would you not want an SSD? The most important reason is price. We hopped onto popular online retailer to do some comparison shopping, and found that the lowest-priced 250GB hard drive was a Western Digital model costing $39.99—in other words, about 16 cents per gigabyte of storage. In contrast, the least-expensive 250GB SSD was an OCZ Vertex costing $375—$1.50 per gigabyte, or nearly 10 times the price. We're not going to pretend the two are equivalent in terms of performance, and many PC owners think that extra speed is worth paying for, but SSDs remain a really pricey (and often unnecessary) proposition for most people.

How Fast?
As we've mentioned, SSDs are basically always going to outrun old-school spinning hard drives, so there's not much point in comparing the two in terms of performance. But if you've decided to buy a hard drive, you'll need to make a choice about speed. Different drives spin at different rates, and the faster you want your data served up, the more you'll usually have to pay to make it happen. The average speed for a desktop hard drive is 7,200 revolutions per minute (rpm), and you can get that right up to the (current) top capacity of 3TB. There are also 10,000-rpm hard drives, which are noticeably faster but available in overall smaller capacities (the largest we found was the 600GB Western Digital VelociRaptor) at a larger price (the VelociRaptor ran about $279.99). Some "low-power," "energy-saving," or "green" hard drives spin even slower and cost even less: Western Digital offers a 5,400-rpm 1TB Caviar Green drive for just $59.99.

The method by which the drive connects to the computer can have a drastic impact on its performance. Most consumer drives these days use Serial ATA (aka SATA), in either the older 3-Gbps or the newer 6-Gbps speed. If your computer's motherboard has a 6-Gbps (SATA III) port, and the drive supports the technology, definitely use it—it operates at twice the speed of the last generation of SATA. If you've had your PC for a while now, it may still use a Parallel ATA (PATA, also known as IDE) port, which is wider and slower than SATA. Though you can still find PATA drives out there, you're better off using the speedier, more-convenient SATA if at all possible. In addition, some newer SSDs will plug into a free PCI Express x16 expansion slot instead of a SATA or PATA port, but this interface is still catching on (and, at present, drives using it are astronomical in price). Other interface technologies, such as Serial Attached SCSI (SAS) rarely show up in consumer systems, so you probably won't need to worry about them.

Form Factor
Most desktop hard drives come in the 3.5-inch form factor, which lets them fit easily into the bays and caddies used in most PC cases. But some newer hard drives, and almost all SSDs, use a still-tinier 2.5-inch form factor. The physical size of a drive doesn't indicate its performance—one of the fastest hard drives out there, the WD VelociRaptor, is a 2.5-inch drive in a 3.5-inch frame—but it can cause problems at installation time. Many cases don't have easy ways to mount 2.5-inch drives, or they require using trays or special brackets that fit in the 3.5-inch drive bays. This all results in a fair amount of potential inconvenience, but adding a super-fast SSD might be worth the trouble.

If you've got more than one hard drive in your system, there's nothing wrong with just letting each one operate independently. But setting them up in a RAID configuration can give you added options, performance, and security. With RAID, which stands for Redundant Array of Independent Disks (or Inexpensive Disks), you can "combine" multiple smaller drives to create one big drive (RAID Level 0, or "striping"), a single "mirrored" drive that offers no added space but guards against data loss (RAID Level 1), or a number of other configurations. Many motherboards today have integrated RAID controllers; check your system or motherboard manual if you're not sure yours does. RAID is too hefty a subject to get into in depth here; if you'd like to learn more, check out the ExtremeTech story, "RAID 101: Understanding Multiple-Drive Storage."

Our Recommendation The drive or drives you choose will depend primarily on your specific computing lifestyle and the amount of money you have to spend. But our personal preference is to buy a modestly sized but fast main drive, such as a 10,000-rpm VelociRaptor or an SSD, and install all your programs on that; and keep a second, bigger drive on hand for our data, even if it spins at slower speeds. (This is where those "green" drives come in handy.) Be sure to choose 6-Gbps SATA drives if your computer supports the technology.

This setup will give you the best overall balance of price, performance, and security, and make it easier for you to further expand your storage capacity later without forcing you to do a full-scale reinstall. Just plug in another storage drive (or two) and you're ready to go.