WHY ADDING RAM IS A GOOD THING
A very common bit of advice we all get from computer people is that if we want to speed up our computer, we should add more RAM, or Random Access Memory. This is good advice, and is usually true. But how does adding RAM achieve this?
THE RAM'S FUNCTION
When you start up your computer, it gets its initial start up instructions from the ROM, or Read Only Memory, which sets up the basic configuration of your PC and enables it to start reading your Hard Drive. After that, all the programs are read from the hard drive, and loaded into your RAM, that is, into the computer's "memory." Your Windows or Mac operating system, your word processor, your internet browser - all these things are loaded into your RAM.
Now, if your RAM is small, say 128 Megabytes, you start running into problems. The operating systems, like windows XP, will use up around 120 Megabytes. Then your Office suite of programs will use up another 100MB or so. But wait! Thats 128 + 120 = 248 Megabytes, and the computer is still able to load more programs! How is that possible?
When your RAM gets full, what the computer does is that it does page swopping. This is when the computer swops blocks of memory, that aren't being used, out of memory and writes them back to the hard drive, into a special area of the hard drive called the Paging File, and it then puts the needed data into this place in the RAM that has been "cleared out."
But here's the rub: RAM is very fast to access, but the hard drive is very (relatively) slow. So when you are running 300 or 400 Megabytes of programs in a 128 Megabyte RAM space, your poor computer is going to be frantically swopping blocks of data between your slow hard drive and your fast RAM. When you're not using your mouse, it swops all the data connected with your mouse out of RAM. When you touch your mouse again, it rushes off to get this data off the hard drive again. So the end result that you experience, is that the computer seems sluggish and unresponsive.
Putting more RAM into your computer means that your PC no longer has to swop data between your hard drive and your computer, so all the activity takes place at the much faster RAM speed. RAM, being a solid state device (ie no moving parts whatsoever), is many hundreds of times faster than a hard drive, which has a spinning disk and magnetic pickup heads, that have to physically move to where the data is on the disk, and read it in.
THE RING ANALOGY.
Think of it this way: Let's say you like to wear rings on your fingers. When your fingers are full, if you want to wear new rings, you'll have to take off some of the ones you're wearing, and put them back in the safe, before you can don the new ones. Getting more RAM is like getting 20 or 40 more fingers to wear your rings on - so you can wear them all at once!
So the more RAM you have, the more programs and graphics you can have running at the same time without slowing your computer down.
HOW MUCH DO YOU NEED?
1 Gigabyte (1,000 Megabytes) will be good enough if your budget is tight. 2 GB is better, especially if you are running Windows Vista, watching lots of movies or doing graphic design, and 4GB or more will keep you humming along no matter what you're doing on your PC.