RAM, or random access memory, is your computers short term memory. It should not be confused with the hard disc, which provides long term storage space for programs and data. When you turn on your computer the information needed by your operating system (Windows) to get the computer up and running is loaded into RAM. When you decide to launch a program, such as a word processor, that program is loaded into RAM and it remains there for as long as the program is being used. If you want to open further programs, these too will occupy a part of the available RAM. As the amount of RAM on any computer is finite, if you open too many programs you will find that you will start to run out of memory, everything will start to slow down and your computer will start to feel unresponsive.
You should remember that RAM only stores information when your computer is turned on - as soon as you switch off your machine all information in RAM is lost.
So what does RAM look like. The most common type of RAM in most home PCs is DDR DIMM RAM - quite a collection of acronyms that stands for double data rate, dual in-line memory module, random access memory. This type of RAM comes on modules like the one in the picture.
RAM modules come in different sizes and the capacity of a module is measured in bytes (a byte allows eight bits (or individual binary numbers) to be stored. Typical modules allow between 64MB (megabytes, or million bytes) and 1GB (gigabytes, or 1000 million bytes). These modules plug directly into the motherboard and most motherboards have slots for between two and four RAM modules. In general, most modern PCs can be fitted with between 512MB and 4GB of RAM. Unfortunately, in order to keep their retail price low, many computer manufacturers used to skimp on the amount of memory that they fitted to their PCs. This is particularly true for PCs that are more than 2-3 years old.
So, how much memory do you need. Quick answer? As much as you can afford! Adding memory to a memory deficient machine is probably the most cost effective upgrade that you can make. If you are running Windows XP then, in our opinion, you should have at least 512MB of RAM. Yes, you can run XP with just 128MB, but as soon as you open more than one application things will start to slow down. With 256MB things improve somewhat, but you will still have slow downs if you are using more than three or four applications or if you have many memory-resident applications running in your system tray (icons in the bottom left of your screen). Depending on the particular PC that you have, 512MB of RAM can be added for between €80-€100 and this can transform a sluggish 3-4 year old machine into a perky one that will meet needs for another few years.
If memory fails it can manifest itself in a number of ways, but random reboots is one of the most common. If your machine tends to reboot for no particular reason while you are using it then faulty RAM is a prime suspect (though there are other possible causes). Another fault that is seen with RAM is module creep, where the module gradually creeps out of the connector. This arises due to the heat/cold cycling of the module and can result in a completely dead machine that refuses to boot. So check for looses RAM modules if your machine shows this behaviour.
Next up, the hard disc, hard drive, disk drive, take your pick.