How Much Memory?

The best philosophy to take when adding RAM to a notebook or laptop computer is "fill 'er up!" Because adding memory speeds up operations and can even extend battery life (up to a point, due to less use of the hard drive for virtual memory swapping), you should normally specify a minimum of 128MB, and preferably 256MB of RAM or more depending on the chipset and processor. If you are a power user or run memory- intensive applications such as photo- and video-editing apps, you might consider 512MB or even up to 1GB of RAM. Most older laptops won't accept nearly that much, so if you are upgrading an older system, the best tip may be to simply install as much memory as you can, with one caveat: I don't recommend installing more than 64MB in older Pentium or AMD 6x86 portable systems, because the chipsets in those systems do not support caching for any memory over 64MB, and installing any memory over that amount will dramatically slow down the system. Newer Celeron, Pentium II/III/4, Athlon/Duron, and Centrino-based systems can cache at least 512MB, and in most cases up to 4GB, so in those systems you can install as much memory as will fit (or that you can afford).

Caution

If your portable computer uses Windows 9x or Windows Me, don't exceed 512MB of RAM because the VCACHE disk cache built in to these versions of Windows can't support the memory addresses needed for this amount of RAM along with the memory addresses required by AGP video. If you want to use more than 512MB of RAM, make sure you are running Windows 2000 or Windows XP.

The amount of memory you use can affect your battery life. Too little memory causes Windows to use the hard disk more often as virtual memory, which means increased disk activity and slower operation. In the end, this adds up to increased power consumption. Adding the right amount of memory to run your applications with a minimum of disk swapping (usually 256MB to 512MB in newer systems) improves performance and increases battery life. Unfortunately, going to extremes by adding up to 1GB of memory may reduce battery life, unless your applications really require that much. More memory often means more memory chips, and those chips need power to operate . If battery life is important, that should be a consideration. The best recommendation is to consult the application program developers for their recommendations on memory. Of course, if battery life is not important to you (for example, you run your system from AC power most of the time), then the more memory the better!

When purchasing a new system, try to get it with all the memory you need right away. Many laptops have only one or two memory module sockets, and in many cases they will already be filled when the system is delivered. This means you will have to remove some of the existing memory in order to add more, which makes future upgrades more expensive.