Seagate / Barracuda 7200.10 / 500GB / 7200 / 16MB / Serial ATA-300 / OEM / Hard Drive Hard Drives Both Big and Small

You can’t open the digital video that shows your niece taking her first steps.  You can’t save pictures.  You are constantly revamping what data you keep, and what you delete.  Sound familiar? You are probably out of hard disk space.  You’re finally ready to upgrade from the factory hard drive included when you bought your PC. Or maybe your building your own computer for the first time.

No matter what, we have compiled a general guide to what’s out there.  The good, the bad, the downright unnecessary.  Read on and rest assured that you’ll have the know-how you need to make the right hard drive purchase this year. 

My Computer has a What Now?

A computer’s hard drive is an integral part of the PC.  The Hard Drive permanently stores the operating system, programs, and data for access.  Hard Drive storage is especially important if you edit movies, play games, or listen to music files on your PC.  A bigger, faster and more reliable internal hard drive can substantially improve your computing ability.  An external hard drive connectible via USB 2.0, FireWire, and external SATA ports is also an option.

What Are Hard Drives Capable Of?

Due to the development of perpendicular magnetic recording, the current maximum capacity for a single drive is 750 GB.  This increase in storage capacity has made it possible to turn your PC into a high-powered multimedia machine.  This provides plenty of room to store all your digital photos, music files, and even those vast video files from your digital camcorder or TV tuner card.  A 750 GB hard drive can store nearly 100 double-layered DVDs worth of video.  There are multiple-disk hard drive applications capable of a terabyte or more of storage capacity.  Hard drives configured with RAID setups or NAS drives for enterprise applications are capable of some of the highest storage capacities ever achieved in the personal computing sector.

What Type of Hard Drive Do I Need?

Seagate / 320GB / 7200 / 16MB / SATA-300 / OEM / Hard Drive When choosing another hard drive, you must decide between internal and external.  An internal drive is a drive located inside your PC, attaching directly to the motherboard or interface card.  An external drive is housed in an enclosure that connects to your PC via USB 2.0, FireWire, or eSATA bus.Iomega Silver / 250GB / 7200 / 2MB / USB 2.0 / External Hard Drive   These are referred to as direct-attached drives because they connect directly to your computer.  NAS drives typically connect via an ethernet connection, in most cases your router.

If you typically use your PC for Web surfing, Microsoft Word documents, e-mail, and light digital imaging, then a lower capacity drive will likely suffice. Go for a 300GB drive, using whichever interface is convenient.  If you store a lot of digital images, audio, or video consider a single 500GB or 750GB drive. If you edit images and video, go for internal or external models that show the best test results on related imaging tasks.  For these jobs an eSATA drive will give you the best performance.  For Gamers, a popular choice is multiple high-speed hard drives connected in a RAID 0 configuration.  RAID stands for Redundant Array of Independant Disks, and will be explained in more detail later on. This technique kicks up performance but limits capacity, because RAID 1 storage is only as good as the smallest hard drive in the configuration.  If you want a NAS device, get the largest capacity available.  All that storage space will go fast when four people are backing up digital photo and MP3 playlists. Get one that’s easily upgraded, in case you might need to swap out a drive.

Internal Drives

Internal drives are suitable for replacing or expanding the storage of a single PC.  Since they reside inside your computer, internal drives provide a convenience and simplicity.  Internal drives consist of tow types:  PATA and SATA.  PATA stands for Parallel Advanced Technology Attachment. These are also commonly referred to as IDE drives.  SATA stands for Serial Advanced Technology Attachment.  Most PCs have room for at least two internal hard disks, and larger towers generally can accept even more drives.

NAS Drives Plextor - PX-EH40L-NA - 400GB Network Attached Storage (NAS) with Built-in USB Print Server

NAS devices allow easy access from any PC attached to your network and can be placed in a relatively safe location.  The biggest drawback is that you need to transfer data via Ethernet, typically using the TCP/IP protocol, this makes NAS the slowest of the three options.

 Beyond Micro / Mobile / 250GB / 7200 / 8MB / USB 2.0 / External Hard DriveExternal Hard Drives

Detachable external drives happen to be more versatile.  These drives let you add storage capacity to a PC if your internal drives are completely full.  They can be shared between multiple PCs and stored in a safe place for use as backup media.  External direct attached drives (attached to the PC with eSATA connection) come in capacities of up to 750 GB for single-drive models and 1 terabyte for two 500 GB drives striped together in a RAID 0 array.  Current external hard drives top out at around 160GB.

Most external drives have a USB 2.0 interface or a dual USB/FireWire interface. 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. FireWire 800 is quite fast, but this interface is relatively rare on desktop PCs. Now eSATA drives featuring direct-attached connectivity are an ever more popular solution. While they don’t offer the universal connectivity of a USB 2.0-enabled drive, they’re as fast as an internal drive and occasionally include a USB connection, just in case. LaCie / Porsche / 500GB / 7200 / 8MB / USB 2.0 / External Hard Drive

External direct attached drives (attached to the PC with eSATA connection) come in capacities of up to 750 GB for single-drive models and 1 terabyte for two 500 GB drives striped together in a RAID 0 array.  Though eSATA drives come with a pass-through connector that provides an external port, they still require an open internal SATA port to use it. If you don’t have an open internal port but do have an available PCI slot, an inexpensive PCI add-in card can provide external SATA, USB 2.0, or FireWire ports for systems that lack them.


Almost all internal drives in currently shipping computers 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 don’t take advantage of wider bandwidth during typical desktop use, however they are particularly productive when placed in RAID configurations.

Prices tend to be similar.  SATA is the newer of the two interfaces.  SATA drives do not require jumper configuration as PATA drives do.  They also have thinner cables that are less restrictive to the flow of air inside your system and are easier to connect.  SATA drives are sometimes slightly faster than PATA drives, but the performance is nearly identical.  You won’t see dramatic performance differences unless you combine the drives in a RAID setup.  There will be more on RAID hard drive applications later in this article.


PATA drives only support maximum transfer rates of either 100mb per second or 133MB per second, but are still widely available.

Although PATA-SATA adapters are available, you should match a PATA drive to a PATA interface for best performance.  SATA drives work only with the SATA interface.  Inexpensive PCI Express and PCI add-in cards are available.  These cards allow you to add an SATA interface to a computer that lacks it.  PATA and PATA/SATA models are available only for PCI.

What Do I Need?

Hard drives are either all about capacity or they’re all about speed.  It is best to choose a drive based on  your needs.  250GB is more space than you’ll need for your operating system, applications, and several years worth of email, documents, and other smaller stuff.  Capacity only matters for people who archive or edit digital photos, digital audio, or video content.

The largest and fastest hard drives always carry a price premium.  The high-capacity flavor of the month will generally drop in price quickly.  However, the high-speed drive will retain its price premium until a faster drive is developed.  The following are several key terms that you must understand in order to purchase the right hard drive. They will help you to better determine exactly what features you want, and what capacity and speed of hard drive is right for your application.

RAID (Redundant Array of Independant Disks) Setup Sans Digital - MS4B - 4-Bay Dual Channel 1394b FireWire RAID External Enclosure

To provide faster performance, premium desktops and multiple-drive NAS boxes often use a RAID setup. The most common of these is called RAID 0.  It splits or stripes data across multiple drives for speed.  Its drawback is that if one drive fails, the data on all drives is lost.  RAID 1 writes data redundantly or mirrored across multiple drives.  If a drive goes bad the system can continue to run on one of the remaining drives until a new drive is installed and the array rebuilt.  The drawback to this approach is that storage capacity is only as large as your smallest drive.  This means that two 250 GB drives paired in RAID 1 provide 250 GB of storage, not 500 GB.  One 250 GB drive paired with a 200 GB drive will only yield 200 GB of mirrored storage.  You can set up your internal drives in a RAID configuration.  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.  10,000-rpm internal SATA 3.5 inch drives are also available.  These are aimed at gaming enthusiasts and IT and computer industry users.

Most PC owners will be fine with 7200-rpm hard drive.  Generally speaking, the faster the disk spins the faster data is read and written.  However, the average buyer won’t want to pay the higher price for a 10.000-rpm model.  Portable external drives have the biggest range in rotational speeds.  The most common of these is 5400rpm. 

Seek Speed

The seek speed refers to how fast drives can find a particular piece of data.  This average is measured in milliseconds.  For most people, the difference in everyday use will be negligible.  Jumbo drives do tend to have longer seek times than drives with less storage capacity.


When a system requests data, hard drives not only fetch what is requested, but also load buffer memory with extra information that the processor is likely to ask for next.  The majority of desktop hard drives will have buffers of either 8MB or 16MB.

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