Tech:Building your own PC/Hard Drives

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The hard drive is a mechanical device used to permanently store your system files, as well as your personal files. It is most likely to be made up of delicate moving parts, so try not to drop or shake it. However new flash based drives called Solid State Drives (SSD) are coming on to the market. These have no moving parts and have many advantages, as well as some disadvantages. Basic things to consider when choosing which one to buy are the interface type, storage capacity, speed, physical size and onboard buffer (sometimes known as cache).

Interface Types

The type of hard drive you need depends on what your motherboard will accept. Laptops commonly use 2.5” hard drives, whereas desktops more commonly use 3.5” drives. The motherboard specification will also tell you whether it needs a SATA or PATA (IDE) drive. Pretty much all new motherboards support SATA, whereas PATA is slowly fading away. Some motherboards have two interfaces to support both types, but if not, adaptor cards which plug into a PCI slot can be used as a last resort. I don’t recommend it though as it won’t do you any favours in terms of performance.

PATA is old technology which allows a maximum bandwidth of 16, 33, 66, 100 or 133MB/s. It connects to the motherboard through the IDE interface, and you are required to set the master and slave device manually and adjust the drive’s jumper settings accordingly. Each hard drive has different jumper settings, which can be found in the manufacturers set up guide.

The newer SATA interface simplifies and speeds up matters, as all you need to do is plug in a cable and it’s ready to use. The SATA cable is a lot thinner, and can be made longer than the IDE cable which it replaced. The advantage here is to keep your case tidy, and it helps to improve airflow. In addition, the original SATA supports speeds of up to 150MB/s, whereas SATAII supports a theoretical maximum of 300MB/s. Even if your motherboard only supports SATA, you can still use a SATAII drive but it’s speed will be limited to 150MB/s. Similarly you can plug a SATA drive into a motherboard supporting SATAII with no problems.

This is an IDE cable:

This is a SATA cable:

You may have heard of SCSI drives. These are even faster but a lot more expensive, so are not commonly used in the consumer market. SCSI hard drives are generally used with server systems, enterprises, and people who demand high speeds for intensive programs with heavy utilisation of the hard drive.

Capacity

Hard drive capacity is measured in bytes. As of today we have conventional hard drives ranging from around 80GB (Gigabytes) up to 2TB (Terabytes). SSDs are available from about 30GB-250GB at the moment in 2.5” form. These are a lot faster than traditional hard drives, and use up less energy, but the high cost and low capacity are the prohibitive factors at the moment.

The amount of hard drive space you need depends on how you use your computer. High Definition videos and software take up a lot of space, whereas smaller files include office documents, pictures and music. Windows Vista recommends a 40GB hard drive but for about £50 you can get a 500GB 3.5” drive or 320GB 2.5” drive. As a guide, with 1GB of space you can fit ~250 mp3 files, 2 hours of DVD quality video or a couple thousand pictures. Most new games these days take up around 7GB of installation space. People who typically only browse the internet, write office documents and have a moderate amount of images could last off a 250GB drive for a while but anyone who is a gamer, downloads lots of videos or music, would be better of getting a 750GB or 1TB drive, keeping in mind future considerations.

Generally to find what hard drive size is the best value for money, you must do a cost/GB calculation. For example if a 500GB drive costs £50 and a 750GB drive costs £100, then the 500GB drive is better value for money as shown below.

£50/500GB = 10.0p/GB £100/750GB = 13.3p/GB

Don’t let this be the deciding factor though. There are other important things to consider as well, such as the drives performance.

Speed

The speed of a hard drive can be found through the manufacturer’s specification. Ideally you want something with a high spin speed, short seek times, large buffer and SATA II. However only you can decide how much you are comfortable with spending.

For the consumer market, you can buy 2.5” drives that spin at 5400rpm, or 3.5” drives that spin at 7200rpm. Western Digital produces a 10,000rpm drive called the VelociRaptor, and is designed for enthusiasts and enterprise users. Although this is a 2.5” drive, it will not fit into a laptop due to its thickness. Some factors which affect the read/write speed are the data density, spin speed and track position. Data density is measured in GB per Platter or GB/square inch. (A hard drive typically has many platters joined together). The higher the data density, the better the sustained read/write speed of the drive. Also consider that as the hard drive gets full it's performance will decrease.

Seek time is expressed in milliseconds. For faster operations you will want a drive with lower seek times. SSDs carry a large benefit here, as there are no moving parts, so the seek time is instant. Every conventional hard drive has a buffer, which is a storage area designed for fast access. In short the higher the amount of buffer, the better your system will perform. Look for a drive with at least 16MB, or 32MB. If you want even faster system performance, you may want to read up on RAID 0 configurations.

Other Considerations

Most hard drives come with a 3 year warranty, but some come with 5. Generally speaking, modern hard drives are quiet, energy efficient and reliable but always back up your important files, in case you are the victim of a virus attack. Some people, such as myself, have installed a fast hard drive to use for the operating system, and kept all the personal files on a separate storage drive. It may be something to consider if you have some spare cash. Even if you only have one drive, I would recommend partitioning it to keep your operating system separate from your own files. This makes it easier in case you need to reinstall the operating system.

If you want to compare performance figures of various hard drives, Tom's Hardware Charts will do that for you.