Buying Guide - Desktop Computers

When purchasing a desktop computer there are a number of factors to consider. Here is an overview of these components so you can understand the differences between different systems.

CPU
The CPU or processor is the brain inside you computer. There are two main manufacturers of CPU's today; Intel and AMD. Both companies are expanding their offerings with 64 bit CPU's and dual and  quad core (and above) CPU's. 64 bit CPU's can handle larger amounts of memory at a time while multi core CPU's have multiple CPU's in a single chip. Additionally there are CPU's designed to use less energy which are primarily used in laptop computers but are increasingly being used in desktop machines.
Performance is roughly measured by clock speed. Current clock speeds run above 3 GHz (Gigahertz)at the high end. There is not an absolute relationship however between clock speed and performance but it can be a good indicator of what to expect. Sometime backing off from  the fastest processor can save a considerable sum with very little performance loss..
There are some significant price differences also with CPU prices running from under $100 to over $1000. Manufacturers of  less expensive systems using less powerful chips also cut costs in other areas to offer a machine that may be $300-$1500 less than a higher end machine.
What does all this mean to you? Generally any system on the market today from the lowest to highest will probably do well for the average user, someone who just wants to type a few letters, balance their checkbook, surf the web and send some e-mail. Unless you are planning to use applications such as Photoshop or voice recognition that will benefit from a more powerful CPU you can get by for several years with a less powerful and less expensive system. However, investing in a more powerful system will extend the life of the system as it will better handle more demanding applications which the future is sure to bring.

Memory
Memory or RAM (Random Access Memory) is where the work in progress is stored. The more programs you want to have open at a time the greater the amount of RAM you will need. The amount of RAM will also vary depending on the operating system installed on your computer. If you have Windows XP you will want to have 512 MB (Megabytes) of RAM or more to operate most efficiently. Systems running Vista, Windows 7 or Windows 8 will probably want at least 4 GB(Gigabytes) Adding additional memory will improve performance on your machine but only up to a point. After that the gains are not as much for the money spent. Memory is fairly inexpensive right now so if given a chance go with the more. You can also add memory later on if you desire, up to the limits your computer supports, but you need to be sure it is compatible with your system. If you are running a 32 bit operating system (XP and 32 bit Vista and above) your allowable memory is 4 GB and you will only get about 3.5 GB useable memory. Theoretically 64 bit operating systems will support up to 16 Exabyte's (an Exabyte is 1 billion gigabytes) but the hardware limitations of current systems will top out at about 128 GB for servers and more like 12-16 GB on desktop machines.
RAM is now coming in several different styles. The differences are in how fast the items in memory can be accessed. DDR 3 is the most common memory right now but other types are available. If you are curious about how much memory your system supports and how many slots you have for memory you can go to crucial.com and run their system scanner. This will tell you how much you have, how much you can have, how many slots for memory you have and how many are already used as well as the type of memory you are using.

Video Card
This is probably one of the most overlooked aspects of a computer system. The video card takes the signals from the CPU and turns them into the display on your screen. A good video card can make a significant difference in the apparent speed of your computer and is especially important if you are planning to play action games. The chip which the video card is based on and the amount of memory available on the card are the two factors which most effect the speed of the card. Low end cards will have 256 to 512 MB of RAM and high end cards will have 1 to 4 GB or more of RAM on them. Some manufacturers use a video chip mounted on the motherboard which has no memory of its own but uses some of the RAM installed on the system. If you are planning to watch DVD or play games on your computer it is essential to get a good video card.
With systems now including many multimedia features it is possible to get a TV tuner card for your system. These allow you to attach an antenna to the card and view TV on your computer or output it to a TV set. Most of these cards include software that allows you to turn your computer into a PVR (Personal Video Recorder) ala Tivo. Some cards include dual tuners allowing you to watch a program while recording another or to record two programs simultaneously.

Hard Drive
The hard drive is where your programs and data are stored. Most hard drives available today are more than large enough for the average user but if you are planning to do picture, sound or video editing on your system you should go for a larger drive as all of these applications use large amounts of disk space. Low end systems now come with 250 GB (Gigabyte) drives but drives of over 2 TB (Terabytes or 1000 GB) are on the market today. Large drives are pretty much overkill for most users unless you have large quantities of music, video or pictures on your computer.
There are also various ways in which the hard drive is attached to the system. Most new computers use SATA (Serial ATA) hard drives. One of the advantages of SATA controllers is that they support RAID (Redundant Array of Inexpensive Drives). What this means is that you can install two drives and have the system automatically use the second one as an exact copy, or mirror, of the primary drive. That way if you ever have a drive failure you can keep working and then replace the bad drive with a good one and recreate the array while still working on your computer. This feature was previously available on SCSI controllers but is much cheaper with SATA. SATA drives also can transfer data at much higher rates than previous drive architectures.
Some systems are now available with Solid State drives. These have no moving parts and are much faster than hard drives. At this time the downside of these drives is capacity and price, costing up to 10 times the price of a similar size hard drive. It is expected that prices will be dropping as the technology matures.
It is also possible to get SCSI drives which operate at a high data transfer rate although they do not have as great an edge as they once did. The newest connector is called Serial ATA. These use a smaller round cable which is supposed to help with keeping the system cooler.

Sound Card
Most systems come with a sound card, frequently as a component of the motherboard. Add in sound cards are also available with a broad range of additional features such as 5.1 or 7.1 surround sound. They also have line in connectors that will allow you to record from another source such as a microphone or tuner.

Modem
If you still need to communicate with other computers over a phone line you must have a modem (MOdulater DEModulator). A modem takes digital signals from the computer and translates them into tones which are sent over the phone lines where they are again turned into digital signals. Most computers today come without modem installed.  If you still need a modem, either for Internet connectivity or some other function such as faxing, be sure to include a modem on your system. Add on modems are always available if your system doesn't come with one.
Modems come in several different types. Many manufacturers install something called a Winmodem. This means that the modem uses software to control many of its functions instead of hardware. This makes them cheaper to produce and lowers the cost of  the computer. Generally they work fine but under certain circumstances they tend to not perform as well and cause frequent disconnects as well as other problems. The other type of modem is referred to as a hardware modem This type has hardware to perform all of its functions. These modems are generally about $30 or more higher than a Winmodem so they tend not to be installed as factory standard.

Optical Drives
CDROMs can read a CDROM disc with a capacity up to 800 MB or read music discs. The speed of a CDROM is stated as 52X where X represents the speed that a music CD plays at. The higher the number in front of the X, the faster the drive can transfer data to the CPU. Despite the number that is not actually the speed that the drive spins at. The speed is valid closest to the center of the disc and slows down as it gets toward the outside of the disc. However almost any drive available today will be fast enough for any use you may have for it.
Other types of drives have become available to install on computers. These include CD Writers, DVD players, DVD Writers, dual layer DVD and Blu-Ray. A CD Writer allows you to write to a blank CD to save data or to make a music CD. CD Rewriteable is the most common form of this type of device. These are capable of erasing and rewriting on special discs designed for that purpose. Rewriteable drives usually have speed ratings such as 24/12/24. This means that it can write a CD at 24X, rewrite a CD at 12X and read a CD at 24 X.
A DVD drive allows you to read DVD movie discs as well as data discs with a capacity of up to 4.5 GB and the dual layer drives can hold almost 9 GB of data.. We are increasingly seeing data disks in the DVD format as the amount of data they hold will eliminate the need for multiple CD's in a set. DVD R/W prices are almost the same as CD/RW or DVD only and it is increasingly difficult to get just a CD drive. There are also several versions so you need to be aware of what you want to do with your disc to determine which kind to get. DVD drives are backwardly compatible with CD's so a DVD can read and write ot CD discs.
The latest drives to appear are the ultra high capacity disks. These were designed to allow HD (High Definition) movies to be recorded on a single disk. Blu-Ray drives are the new standard for watching high definition movies. They can hold up to 27 Gigabytes of data on a single disc.

Operating System
Your computer will probably come with some variation of Windows on it. Windows 7 is the current version and probably provides the greatest stability and richness of features to date. It comes in home, professional and ultimate versions in both 32 and 64 bit versions. Most systems now come with the 64 bit version installed. The home version is acceptable for most users but the professional version is preferable in an office environment.  Windows 7 provides increased security as well as a new look to the interface. All versions include Media Center which allows you to have all your media in one place, including TV if you have a TV tuner on your computer.
There is an alternative operating system available on systems called LINUX. LINUX has primarily been used in back end servers but it is now beginning to get some decent front ends which make it acceptable for desktop use. It is not compatible with Windows programs (although we are seeing software which allows some Windows functionality) so if there is a program you use that is only available in Windows format LINUX is not going to work for you.
Finally, there is the MAC OSX operating system. This is only available on computers from Apple Computer and is incompatible with Windows programs however it is possible to install Windows on an Apple computer.

Additional Features
All computers come with ports on them. These are where you can plug in cables to attach additional peripherals to your computer such as a printer or scanner. Most systems come with a serial port, a network port and USB ports. USB is replacing the parallel and serial ports on computers. Some systems are now beginning to eliminate serial and parallel ports so if you have older peripherals that require these types of ports check to be sure they are included. It is possible to add them to most systems if you need them.
USB (Universal Serial Bus) is now common as a way to attach peripherals. Through the use of hubs it is theoretically possible to have as many as 127 devices attached to your computer at once. It is now possible to buy digital cameras, scanners, and printers that attach to your system with USB. Most computers now come with USB 2.0 but systems with USB 3.0 are now starting to show up.  USB 2.0 and 3.0 are backwardly compatible with the USB 1.1 standard.
Another connector is known as either Firewire (trademarked by Apple) or IEEE 1384. This is a high speed bus ideal for devices such as Digital Video Cameras. Many Digital Video Cameras use this method of connection. If you think you may wish to edit your digital videos you might want to look for a system that already includes this port, although it can be added to a system for about $35.

Use the Comparison Sheet

Use the comparison sheet to decide on what model to buy. This allows you to decide on the features you want and compare that to the models you are interested in. It will probably be impossible to find a model with all of the features you want so be prepared to compromise some. Some companies like Dell allow you to customize their systems but even those will not necessarily give you all the features your want.