How to Buy a Hard Drive

When a system requests data, a hard drive will fetch what is requested and 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. Most desktop drives--and all of the ones on our Top 5 charts--have buffers of either 8MB or 16MB. Value-priced PATA drives may have 2MB buffers.

If you are building your own PC to use in your living room as a media center hub, noise may be a significant issue. Many hard-drive makers offer versions of their drives designed for use in personal video recorder or media-streaming environments. Look for these specialty drives if you're looking to reduce the noise output by your system.

Hard-Drive Shopping Tips

Are you ready to take the plunge and buy a big new hard drive for your PC? Here arePC World's recommendations for what you should consider, both before you buy the drive and when you're actually shopping.

Determine whether your PC can take advantage of a new drive. Newer PCs can make best use of a new drive's increased performance and capacity. An old PC with a slow CPU and limited RAM won't be able to fully exploit the performance potential of a new drive. You've probably reached the point of diminishing returns 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 various productivity applications might improve performance appreciably. 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 capacity of large drives; Windows XP's drivers allow use of a drive's full capacity as well.

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 a smaller, low-profile case, you may not have room for another internal drive, meaning that you may not be able to use the old and new drives simultaneously.

Also, check your power supply to see whether it has a spare plug for an additional internal drive. Another consideration: Will the power supply have enough juice to run an extra drive along with your system's existing 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 programs that edit video), or storing digital photos or MP3 audio files, you might not need a maximum-capacity drive. 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 faster than the internal interfaces on many older PCs; check your PC manual or contact your computer vendor to find out for sure. An easy-to-install interface card (about $25) can guarantee that you get maximum performance from your new drive. If you want to add a SATA-300 drive to a system with SATA-150 connectors, however, 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 the 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 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. One relevant feature is a ruggedized enclosure with a high shock rating, meaning that it can absorb a typical impact from a desk to the floor, for example. Some drives may also have g-force sensors that can detect when a drive is in motion and park the heads to avoid damage to the disk. Typically, though, that feature is found on internal notebook drives, rather than on add-on drives.