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Buying a Computer

Hard drive

The hard drive on your PC is a storage device, sort of like a digital briefcase where you keep all your important data. It works by rapidly recording data with magnetic pulses on spinning metal platters. The more quickly a drive spins, the quicker you can access and transfer data.

Hard drives come in a number of sizes, but 3.5in is by the far the most common type for PC computers. Most computer cases are designed to fit 3.5in drives.

The drive contains a motor that spins the platters at speeds from 5,400 to 15,000 revolutions per minute (RPM). The more quickly the drive spins, the more quickly you can read and store data.

Aim for a hard drive with a rotational speed of 7200rpm over the older 5400rpm models. This will offer the best price/performance balance.


What sizes do hard drives come in?

The minimum size your hard drive will come in these days has risen significantly over the past 12 months, and consumers should be able to find a sub-$1000 desktop PC with between 60GB and 200GB of hard disk drive space. Drives with up to 500GB storage are currently available, although you pay a significant premium for hard disks at the top-end of the capacity spectrum. If you plan on storing large amounts of data on your hard drive, such as digital images or multimedia files, then the bigger the hard drive, the better.

As an example, we've used an 80GB hard drive to illustrate the amount of storage space you'll need to house the following files:

  • Depending on various quality and file format settings used, one minute of near CD-quality music will use around about 1MB of memory. This means that a 5GB player could hold roughly 1000 five-minute songs. Therefore 4000 songs in MP3 format: 20GB
  • 3 PC games (such as Unreal Tournament II, at 3GB each): 9GB
  • 2 hours of DV footage: 25.60GB
  • 4 hours of recorded TV shows: 4GB
  • Windows XP: 1.5GB
  • 2 years of stored Outlook e-mail messages for a heavy user: 4GB
  • 11 applications, including Office XP Professional, Norton AntiVirus and Adobe Photoshop: 1.88GB
  • 1500 JPEG photos (1600x1200 each): 1.41GB
  • Hundreds of Excel spreadsheets, Word documents and Acrobat files: 1.08GB
  • FREE SPACE REMAINING: 11.55GB


What are the hard drive interfaces?

The drive interface is the "language" a drive uses to communicate with a PC. The two main types of PC hard drive interfaces are the ATA (Advanced Technology Attachment), also known as the IDE interface, and SATA. SCSI (pronounced "skuzzy") is also available, but less common.

The ATA and SCSI interfaces have evolved to include many sub-types, which may or may not be backwards compatible. SCSI disk drives are expensive, require expensive controller cards and typically are only used on high-end workstations and servers. Virtually every PC motherboard has a built-in IDE hard disk controller, which has two connectors called a Primary and Secondary channel. Each channel can support one or two IDE drives, making a total of four possible drives. These could include hard disks, CD/DVD drives, CD writers, or a Zip drive.

The original ATA interface supported a maximum transfer rate of 8.3MBps. The last three evolutions allow up to 33, 66,100 or 133MBps to be transferred. Today, these numbers are often prefaced with the word Ultra-DMA or UDMA (ultra direct memory access). Ultra-DMA is also known as Ultra-ATA or EIDE, and typically will be advertised as Ultra ATA/33, UltraATA/66, Ultra ATA/100 and now UltraATA/133.


Serial ATA

More recent and more advanced than IDE, serial ATA, or SATA, was designed to replace parallel ATA (IDE). Users will benefit from SATA by being able to easily upgrade their storage devices, while configuration of SATA devices will be much simpler as jumper and settings are no longer needed. SATA hard disk drives will work with current operating systems and are software compatible with parallel ATA. Many existing motherboards support both SATA and PATA. Older motherboards may only support IDE.

The biggest benefit of SATA is its increased data transfer rates. While the fastest performing parallel ATA drives offer data transfer speeds of 133MHz, SATA operates with a data transfer speed of 150MHz. SATA drives also take up less room within the PC case due to smaller cabling (making them great for use within compact systems).

Although prices for SATA drives were initially higher than parallel ATA drives, there is now little difference in price between the two technologies.
   

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