The storage place for all types of data, from your operating system to video and sound files to games. An often overlooked component, the quality and speed can have a big impact on the performance of the entire machine, especially in terms of load times and failure rates. Old systems had hard drives of a few hundred megabytes (MB), but nowadays hard drive sizes of 80GB (1GB = 1024MB) and larger are commonplace. In this FAQ I will deal only with ATA and sATA drives, as SCSI drives are rare in desktop machines, and are a completely different technology altogether.

This is usually the rotation speed of the platters within the hard drive, in revolutions per minute (rpm). Older drives were 3600rpm and 4200rpm, but nowadays drives with speeds of 5400rpm, 7200rpm (the most common) and 10000rpm are the standard. The faster the hard drive’s speed, the lower the seek time.

The delay between when a CPU requests data from the hard drive, and when the first byte of data is sent to the CPU is know as the seek time. Measured in milliseconds, it is a popular measure of the performance of a hard drive. The lower the seek time, the faster the hard drive is. Hard drives that are sold today typically have a seek time of 9-12 milliseconds.

There are two common interfaces around presently: parallel ATA (PATA, sometimes abbreviated to just ATA) and serial ATA (SATA). SATA is the newer technology, which will improve in theoretical speed from 150MB/s now to around 600MB/s in 2007 (according to Seagate). ATA stands for Advanced Technology Architecture, and PATA being used since the early 1980s are the industry standard in desktop hard drives. This technology has now aged and is about the oldest piece of technology to be found in a computer system today. PATA has allowed expandibility like no other computer technology, but has reached the end of its usefulness as it reaches its limits. SATA is the next step for hard drive technology, it has much smaller cables, allows “hot-swapping” (taking out/adding in drives while the computer is on), and is also much faster. 72MB/s is the current maximum for ATA100 drives, but this will be dramatically increased as IDE technology improves over the next couple of years.

These days, motherboard’s chipsets usually have SATA build into them, while with older motherboards you can buy SATA controllers that usually plug into a PCI slot. Gone are the bulky PATA cables too!

Like a CPU, hard drives have caches where recent data is stored, ready for use again if needed. Most drives today have either 2MB, 8MB or 16MB caches. This makes drives quite a bit faster, but also makes them a bit more expensive.

Measured in GB, the capacity of hard drives can range from anywhere between 20GB up to 750GB. Common sizes are around the 200GB to 300GB mark, and can be bought cheaply (less than $1 per GB).

As hard drives get faster, they also get hotter (similar to CPUs). Having airflow over a hard drive is essential for improving a hard drive’s life expectancy. Many enthusiasts now include front panel fans as essential components for their systems, to direct airflow over their drives. Hard drives can reach temperatures in excess of 40 degrees! That heat has to go somewhere, and it’s best if doesn’t stay in the hard drive itself, but is convected out into the case, and then out of the case.

Major players: Western Digital, Seagate, IBM/Hitachi - there are a few other smaller manufacturers, but these are the major ones.

Arguably produces the fastest hard drives, but they are often hot and noisy as well. Western Digital offers three year warranties on all of their drives. They aren’t the cheapest drives around, but they make up for this in improved performance and quality. They have also recently released the Raptor series of SATA drives, that spin at 10,000rpm and compete with many SCSI drives in terms of performance. However, these drives are currently only available in sizes up to 150GB and are much more costly per gigabyte that regular ATA and SATA drives, so are limited to enthusiasts only.

One of the oldest manufacturers of hard drives, Seagate is known for its well-priced, quiet and cool drives, and their Barracuda series of drives are highly popular for their large sizes and relatively low prices. Their performance is perhaps not as good as Western Digital, but they are good drives overall. Seagate drives come with come with five year warranties. They were the first to release a desktop SATA solution, and are also known for their high-speed Cheetah series of SCSI drives that spin at 15,000rpm.

Maxtor purchased Quantum a while back, and in turn were themselves purchased by Seagate in May 2006. In the past, Maxtor have had problems with their Quantum Fireball and Bigfoot drives, but their later drives were top-quality. They also offered the only ATA133 drives, which were mostly pointless in terms of actual performance. Price-wise, they were usually placed between Seagate and Western Digital.

Hitachi and IBM merged their hard drive operations in December 2002, and now produce top-notch drives for desktops, laptops and servers. Typically more expensive than Western Digital, they are quiet drives, with good performance. The quality control of their drives has improved drastically over the years (their reputation was damaged several years ago with the release of a bad batch of Deskstar hard drives). Their drives have either a one year or a three year warranty (it pays to check).