The amount of RAM you use is dependent on the purpose that you want to use it for. Older
versions of Windows and Linux will run comfortably, though slowly at times, on 128 MB.
Some newer operating systems such as Windows XP require 256MB of RAM to run
comfortably. Many people now have 512 MB or more for better performance. Users of modern
games and graphics software, or people who may wish to host Internet services such as a Web
site, may want 1 GB or more.
Another thing to consider when choosing the amount of RAM for your system is your graphics
card. Most motherboard-integrated graphics chips and PCI Express graphics cards marketed
with the "Turbo Cache" feature will use system memory to store information related to
rendering graphics; this system memory is generally not available at all to the operating system.
On average, these graphics processors will use between 16MB and 128MB of system memory
for rendering purposes.
The actual type of RAM you will need will depend on the motherboard and chipset you get.
Most current motherboards use DDR (Double Data Rate) RAM. The Intel 915/925 chipsets use
DDR2 RAM. Chipsets that use dual-channel memory require you to use two identical (in terms
of size and speed) sticks of RAM. Your RAM should usually operate at the same clock speed
as the CPU's Front Side Bus (FSB). Your motherboard may not be able to run RAM slower
than the FSB, and using RAM faster than the FSB will simply have it run at the same speed as
your FSB. Buying low-latency RAM will help with overclocking your FSB, which can be of
use to people who want to get more speed from their system.
If you are upgrading from an existing computer, it is best to check with a user group to see if
your machine requires specific kinds of RAM. Many computer OEMs, such as Gateway and
HP, require custom RAM, and generic RAM available from most computer stores may cause
compatibility problems in such systems.
RAM have different bandwidths, ie 400, 533, 600, 733, 800, the current trend is moving from
DDR2-400 RAM to DDR2-533 RAM as it is more efficient. Higher end models are very
expensive unless you find it worth the investment.
Labeling of RAM
RAM are labelled by its Memory Size (In MB) and clockspeed (or bandwidth).
•SDRAM (Synchronous Dynamic RAM) is labeled by its clock speed in megahertz (MHz). For
example, PC133 RAM runs at 133MHz. SDRAM is nearly obsolete as nearly all motherboards
have withdrawn support for SDRAM. It is now superceded by the more efficient DDR RAM.
•128MB SD-133 = 128MB PC133 RAM
•DDR RAM can be labeled in two different ways. It can be labeled by approximate bandwidth;
as an example, 400MHz-effective DDR RAM has approximately 3.2GB/s of bandwidth, so it is
commonly labeled as PC3200. It can also be labeled by its effective clock speed; 400MHz
effective DDR RAM is also known as DDR-400. There is also DDR and DDR2 labelled as PC
•256MB DDR-400 = 256MB PC 3200 RAM
•256MB DDR2-400 = 256MB PC2 3200 RAM
DDR RAM has two versions DDR (also DDRI) and DDR2 (or DDRII)
•DDR supports DDR-100, DDR-200, DDR-300, DDR-400 (mainstream) and DDR-533 (rare)
•DDR2 supports DDR-400, DDR-533 (mainstream) and rare/expensive DDR-600, DDR-733,
DDR-800, DDR-933, DDR-1066