What are the key components of a personal computer? What is their function? Below I will list components that are necessary for a computer to operate using non-technical descriptions of their functions.
Hard Drive: This is not memory. A hard drive has no more memory than a floppy disk. In fact, it performs the same function as a floppy disk. It holds data. Floppy disks, Zip disks, CD-R/RW disks, DVD-R/RW disks, Flash Drives and Tape cartridges are just some of the other mediums that store data. A book stores data. When you close a book the data remains. When you turn off a computer the data remains on the hard drive. A hard drive is a large capacity storage medium.
Capacity, RPM, and type of data cable
The larger capacity a hard drive the more data it can store. Another consideration is the speed of the hard drive. In general, the faster a hard drive spins the faster it works for you. For a home computer there are two speeds to look at - 5400 RPM drives and 7200 RPM drives. Most hard drives on the market today spin at 7200 RPM. Lastly, the cable that transfers data from and to the hard drive is changing. The IDE cable which has been used for years is changing to the SATA, Serial ATA, cable, a much narrower cable that transfers data considerably faster than the IDE cable.
Memory: Also called Random Access Memory or RAM. Data is not stored in memory. It resides in memory only as long as the computer remains powered on. When a computer is turned on and the operating system begins to load, data is sent to memory. Almost everything you see on the screen, every keystroke, every click of the mouse is processed through memory. Some of the data remains in memory. For example, some data is sent to the monitor via the video adapter as well as other components when required. The operating system manages the swapping of data in and out of memory. Some operating systems are better at managing data/memory better than others.
So okay, it looks like the more memory you have the better. With Windows XP that's true. Windows 95, Windows 98, and Windows ME do not manage memory very well and may not be able to use memory much over 128mb. Some sophisticated games and programs takeover memory management when launched and may use more. Windows 2000 and Windows XP however, manages memory very well and can and will use as much memory as today's motherboards can take.
There are 2 types to be concerned with - standard SDRAM or DDR (Double Data Rate). DDR memory can move data faster than it's predecessor and is specifically fabricated to handle the fast through-put necessary to keep up with the fastest CPU's.
Central Processing Unit (CPU): The CPU processes everything! If your typing a letter the CPU processes the keystrokes and sends the information to the video adapter and to memory so you can view it. When you save it the processor instructs the operating system to write it to the hard drive. Needless to say the faster data is processed the faster your system carries out those instructions. CAD CAM programs and games are among the things that require large amounts of data to be processed.
One of the main parts of a CPU that directly affects processing speed is called cache. A CPU uses cache to hold the most often used instruction that the operating system uses to perform all of its functions. When a PC is first turned on these instructions are read from the hard drive's system files. A hard drive is infinitely slower than a CPU so the system monitors all the thousands of instructions being executed and caches those used most in special cache chips thus speeding up the processing of those instructions.
The bottom line here is the faster the processor the higher the cost.
Video Adapter: The video adapter sends data to the monitor so you can see what your doing. Gamers want one that can process their game as fast as possible. Every video adapter has memory on board that holds the image and data it sends to the monitor. The more memory a video adapter has the more efficient it is at doing it's job. For game playing I recommend an adapter with a minimum of 256mb of memory.
Motherboard: All the above parts reside in or plug into the mainboard. Many of the systems sold in retail stores, mail order, and on the Internet have some or all of the above parts integrated into the motherboard. The main reason this is done is to bring the cost down. The problem with this is poor or no upgradeability and the overall system does not perform as efficiently as one with plug and play components.
Most motherboards today have integrated sound and network adapters.
Power Supply: The power supply, as it's name refers, supplies power to all the above parts via the motherboard. A power supply is bought by how many watts it puts out. The higher the wattage the more add-on adapters can be efficiently used. A low watt power supply may overwork and die prematurely. I recommend at least a 300 watt power supply. PC Whizdom stocks an industry standard 430 watt power supply.
All the above parts delineated above are some of the most important parts in a personal computer. One is no more important than the other because without any one of these the system would not function. A PC is only as good as the sum of these parts. Let me put it another way. An inexpensive PC may not be built with inferior parts but with parts manufactured to perform very low end functions. As long as it is used for only low end functions it should perform as expected. But if bought strictly for cost with the expectation of performing the higher functions of its bigger brothers the user will be disappointed.