Where the rubber meets the road, your PC's internal hard drive is the real workhorse--the most critical component of your system after the CPU and memory. It's where your operating system, programs, and data are permanently stored and accessed.
If you edit movies, play games, or listen to music files on your PC, a bigger, faster, and more reliable internal hard drive can dramatically improve your overall computing experience. If you need more storage or a means to back up your PC's internal drives, you can add an external hard drive -- available in USB 2.0, FireWire, or external SATA flavours. And if you want centralised storage, consider buying a network attached storage device. NAS devices are continually improving, and can be a convenient way to add storage that can be shared between all the PCs on your small or home network.
The Big Picture
Today's hard drives have stunning capacities: With the advent of perpendicular magnetic recording, 750GB is the current maximum capacity for a single drive. And as always, the drive you buy today will give you more gigabytes for less money than the one you could have bought a year ago.
This increased storage capacity has made it possible and even economical to turn your PC into a high-powered multimedia machine with plenty of room to store all your digital photos, a raft of digital music files, and even those vast video files from your digital camcorder or from a TV tuner card. A single 750GB hard drive can store nearly 100 double-layered DVDs' worth of video.
Innie or Outtie?
When shopping for a hard drive, your first decision is whether to go internal or external. By internal drive, we mean a bare drive that goes inside your PC, attaching directly to the motherboard or interface card. An external, direct-attached drive uses the same basic mechanism, but it's housed in an enclosure that connects to your PC via the USB 2.0, FireWire, or eSATA bus. Also available are external NAS devices that connect via ethernet, typically to your router.
On one hand, internal drives are suitable for replacing or expanding the storage of a single PC. Since they reside inside your PC, they provide a convenient out-of-sight, out-of-mind experience. Detachable external drives, on the other hand, are more versatile. These drives let you add storage capacity to a PC with internal drive bays or connections that are maxed out. They can be shared amongst multiple PCs and stored in a safe place when used as backup media.
NAS devices allow easy access from any PC attached to your network and can be placed in a relatively safe location. They also tend to offer perks like printer and Internet file access so you can easily share printers across the network or access files from anywhere on the web. NAS's biggest drawback is that you need to transfer data via ethernet, typically using the TCP/IP protocol; this generally makes NAS your slowest option.
Internal drives commonly appear in two flavours: PATA (Parallel Advanced Technology Attachment, also commonly called IDE drives) and SATA (Serial ATA). All things being equal, and prices generally are, opt for SATA, the newer of the two interfaces (if your PC supports that connection). SATA drives don't require you to configure jumpers as PATA drives do; their thinner cables are less restrictive to the flow of air inside your system; and they are easier to connect. SATA drives are sometimes ever-so-slightly faster than PATA drives, but often the performance is nearly identical; you won't see a dramatic performance difference unless you combine drives in a RAID (Redundant Array of Independent Disks) setup. Still, you can be assured that SATA drives will be supported on the motherboard of any PC you purchase in the foreseeable future, whereas PATA drives may not be.
In the end, hard drives are either all about capacity or they're all about speed--depending on your needs. Though our tests show that today's hard drives all perform adequately when running regular business applications, capacious, speedy drives particularly benefit people who process large files, images, and digital video.
Alas, all other things being equal, the largest-capacity and fastest hard drives always carry a price premium. But chances are that before long you'll be able to find this month's high-capacity model at a much more affordable price. By contrast, high-performance drives tend to stay more expensive for longer--until their next capacity bump-up comes along.
Key Features
Capacity: Even relatively inexpensive PCs typically come with hard drives of at least 250GB, which is far more space than you'll need for an operating system, applications, and several years' worth of email messages and typical documents. Capacity really matters for people who archive or edit digital photos, or digital audio or video content. Video in particular can be a space hog: For example, the contents of a 1-hour MiniDV camcorder tape can consume 13GB.
If you want high capacity inside your desktop, remember that you don't have to get it all in one package: Most PCs have room for at least two internal hard disks, and a big tower generally can accept even more drives. You'll usually save money by purchasing two 250GB drives instead of a single 500GB model at a premium. But keep an eye out for rebates and advertised specials; for example, with promotions, you may be able to find that 500GB model at a comparable price to the two 250GB models. And of course, make sure that you have available interface ports; if not, you may have to purchase an add-in card.
External direct-attached drives come in capacities of up to 750GB for single-drive models and 1 terabyte for two 500GB drives striped together in a RAID 0 array. Portable external drives, which use a notebook-sized 2.5-inch or 1.8-inch hard disk, currently max out at 160GB. Affordable, single-drive NAS boxes range from 160GB to 750GB, while more-sophisticated multiple drive units can be configured in a variety of ways for greater capacities of up to 3TB and/or speed. Generally speaking, it's wise to go for as much capacity as you can afford, especially for a shared network drive that multiple users will fill more quickly.
RAID setups: To provide faster performance, high-end desktops and multiple-drive NAS boxes often use RAID. RAID 0, the most common setup, splits or stripes data across multiple drives for speed. Its drawback is that if one drive fails, the data on all drives is lost--so you'll need to keep your backups current.
For systems that can't afford a lot of down time, RAID 1--in which data is written redundantly or mirrored across multiple drives--is often used. If a drive goes bad, the system can continue to run on a good one until you can install a new drive and rebuild the array. The drawback to this approach is that the usable capacity is only as large as the smallest drive being used--two 250GB drive paired in RAID 1 provide 250GB of storage, not 500GB, and one 250GB drive paired with a 200GB drive would yield only 200GB of mirrored storage.
Typically, dual-drive RAID boxes offer the choice of RAID 0 or RAID 1. Multiple-drive direct-attached or network-attached boxes -- some enclosures support up to five drive bays -- generally complement those basic RAID levels with RAID 5 or RAID 10 (a combination of RAID 1 and RAID 0).
You can also set up a RAID for your internal drives; however, your motherboard or add-in drive controller must support RAID.
Rotational speed: All 3.5-inch, desktop-sized internal SATA hard drives--and most current PATA drives--spin their disks at 7200 revolutions per minute. There are some 10,000-rpm internal SATA 3.5-inch drives available as well, aimed at enthusiasts and enterprise users. Yesterday's bread-and-butter 5400-rpm PATA drives are becoming scarce, although you probably can find some on dusty store shelves. Most buyers will be better served by a 7200-rpm model. Typically, the faster the disks spin, the faster the data is read and written--but the average buyer won't want to pay a price premium for a 10,000 rpm model.
Portable external drives have the biggest range in rotational speeds. Models are currently available in 4200-rpm, 5400-rpm, and 7200-rpm flavours. The most common of these is 5400 rpm.
Seek speed: Average seek speed, measured in milliseconds, refers to how fast, on average, drives can find a particular piece of data. This is a minor consideration: For most people, the differences in everyday use will be negligible. The exception is when many small pieces of data scattered in different areas of the hard drive need to be assembled, such as when copying large folders full of many small files. Jumbo drives tend to have somewhat longer seek times.
Interface: Nearly all internal drives in new PCs use the SATA interface, which supports maximum transfer rates of either 150MB or 300MB per second. The drives with a 300MB-per-second maximum transfer rate cannot take advantage of their wider bandwidth in typical desktop use, though they shine in RAID combinations.
PATA drives, which support maximum transfer rates of either 100MB per second or 133MB per second, are still widely available. There's little advantage to one or the other; hard drives never sustain data-transfer rates approaching either, though drives can sometimes push out brief bursts of data approaching the higher speeds.
PATA and SATA interfaces are both backwards compatible: For example, you can run an older ATA-33 drive on an ATA-133 bus or a 150MB-per-second SATA drive on a 300MB-per-second bus. But although PATA-to-SATA adapters are available, you should match a PATA drive to a PATA interface whenever possible to get the best performance. SATA drives work with the SATA interface only. Inexpensive PCI Express and PCI add-in cards are available that let you add a SATA interface to a computer that lacks it; PATA and PATA/SATA models are available only for PCI.
Most external drives have a USB 2.0 interface or a dual USB/FireWire interface. FireWire 800 is sometimes thrown in the mix. Performance on any of these interfaces is slower than you'd find with a comparable internal drive, but it's acceptable for auxiliary storage or backup. If you need speed, however, turn to an eSATA direct-attached drive: eSATA drives are becoming more popular, and while they don't offer the universal connectivity of a USB 2.0-enabled drive, they're as fast as an internal drive--and sometimes include a USB connection, for good measure.
A USB 2.0 drive will work with a USB 1.1 port, but performance is reduced to an unacceptably slow level. Inexpensive PCI add-in cards can provide USB 2.0, FireWire, or eSATA ports for systems that lack them; likewise, you can find PC Card adapters that add USB 2.0 and FireWire ports to a notebook if your system is old enough to lack these interfaces. However, FireWire and FireWire 800 use different connectors, so they are not cross-compatible.
Consumer-level NAS devices generally employ the TCP/IP protocol and a 10/100Base-T or gigabit ethernet connection to hook up to your network. As such, NAS devices are generally poky when compared with direct-attached external models. Look for NAS devices that provide USB 2.0 ports for adding additional hard drives to expand capacity or attaching printers to be shared across the network.
Buffer: When a system requests data, a hard drive will not only fetch what is requested, but it will also load its buffer memory with extra information that the processor is likely to ask for next. Theoretically at least, a larger buffer size should help keep the data flowing better, especially in disk-intensive tasks such as file searching. The majority of desktop drives will have buffers of either 8MB or 16MB. Value-priced PATA drives may have 2MB buffers.
Hard Drive Shopping Tips
Are you ready to take the plunge and buy a big new hard drive for your PC? Here are PC World's recommendations for what you should consider, both before you buy the drive and when you're actually shopping.
Can your PC take advantage of your new drive? Newer PCs can best maximize a new drive's increased performance and capacity. A really old PC with a slow CPU and limited RAM won't be able to use the full performance potential of a new drive; you may reach the point of diminishing returns. You've probably reached this point if your PC's interface speed, say ATA-33, is slower than the interface speed of the cheapest drive available.
If your middle-aged computer is still working acceptably, more storage capacity and speed may be just what the doctor ordered. Installing a new drive as your main drive for running Microsoft Windows and productivity applications might create an appreciable performance improvement. Older PCs may need both a PCI interface card to get the best drive performance and a vendor-supplied driver or BIOS update to be able to recognize the full capacity of large drives; Windows XP's drivers also allow full capacity.
Make sure your case has space. Most desktop PC cases have at least one, and sometimes several, internal drive bays--places where you can mount extra hard drives. But check your manual, or open the case: If you have one of the smaller low-profile cases, you may not have room for additional internal drives. You wouldn't be able to use both the old and new drive at the same time.
Also, check your power supply to see if it has a spare plug for another internal drive. Another consideration: Will the power supply have enough juice to accommodate an additional drive along with your existing system components?
Supersize your purchase. It's smart to buy a drive with more capacity than you think you'll need. If you're absolutely sure that you won't be using multimedia-intensive applications that eat up huge amounts of space (such as editing video or storing digital photos or MP3 audio files), you might not need one of the largest-capacity drives. But be sure to anticipate your future needs when deciding on the size of your new drive, especially if you plan to keep your existing PC for a couple more years.
Match the drive and interface speed. The ATA-100 and ATA-133 interfaces of current drives are often faster than the internal interfaces on an older PC; check your PC manual or contact your computer vendor to find out. An easy-to-install interface card can ensure that you get maximum performance from your new drive. However, if you want to add a SATA-300 drive to a system with SATA-150 connectors, just do it. The nominally slower interface should not choke the performance of a SATA-300 drive.
Use an external drive for backup. External drives are great for backing up your PC, and many models have one-touch backup buttons that make that process even easier. The fastest external hard drives are the new eSATA models. Make sure that you have at least one free internal SATA port for models that come with a pass-through cable, or buy a model that offers eSATA ports through a PCI interface.
Use a portable drive with your notebook. External models that use hard drives intended for laptops tend to be optimized for mobile use. This includes such typical features as g-force sensors that can detect if a drive is in motion and park the heads to avoid damage to the disk, and a ruggedized enclosure designed to withstand a typical impact from a desk to the floor, for example.
Consider a NAS device. They're a great choice for backup as well as making photos, videos, music, and other files available to everyone on your network. NAS devices connect to your network via ethernet, which means middling performance, but also typically include USB 2.0 ports to share a printer or to expand storage capacity should you run short in the future.
Look for bargains. Competition among hard-drive makers is intense, and dealers often run specials that let you pick up a new drive for an amazingly low price. These deals tend to be on smaller-capacity or slower drives, however. Don't expect specials on the largest-capacity drives; they're often in short supply, so they sell at close to list price until the next generation of drives appears.
Buy a retail kit. Hard-drive kits include mounting hardware, cables, detailed instructions, and (often) software that eases installation. A kit can also include an application for cloning your old hard drive onto the new one, which can then become your new main drive. If you're buying via mail order, be sure you're getting the kit. The alternative is a "bare drive," essentially just a drive in a Mylar bag, often with no screws, software, or even instructions beyond a technical data sheet. Bare drives can sometimes be purchased online at bargain prices, though, and plenty of online installation help is available.
Use add-on software. Power users who purchase a bare drive and aren't running Windows XP may need extra software to ease the process of integrating the new hard drive into their PC. Even if you buy a packaged drive upgrade kit, you might find the Symantec's Ghost or Acronis True Image helpful for backing up and cloning a drive. Symantec's Partition Magic and Acronis's Disk Director let you fine-tune how data is stored on your new drive.
Final Recommendations
General use: If you typically use your PC for Web surfing, Microsoft Word documents, email, and casual digital imaging, then a lower capacity drive may work for you. Opt for an inexpensive 300GB drive, using whichever interface is convenient for your needs.
Multimedia hounds: If you store a lot of digital images, audio, or video, you should consider either a single 500GB or 750GB drive.
Gamers: A popular choice for performance-hungry gamers is a RAID 0 rig with two Western Digital 10,000-rpm WD Raptor drives. This kicks up your performance but limits capacity, since the WD Raptor is available only in 36GB, 74GB, and 150GB sizes as of this writing.
Shared storage: If you want a NAS device, get the largest capacity you can find -- those gigabytes will go fast when four people in your household are backing up their digital photo and MP3 collections. And aim for one that's easily user-upgradeable, in case you need to swap out a drive down the road.