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Differences in Notebook Memory and
Desktop Memory
Desktop PC Memory (DIMM)
There is many
RAM types available for desktop computers.
Most commonly used types are DIMMS (Dual In-Line Memory Module). DIMMS
are small circuit boards that hold the memory chips, they are also standard in
desktop computers. Some of the more
common types of DIMMS are:

1. SDRAM
– Synchronous Dynamic Random-Access Memory
·
Short for Synchronous DRAM, this type of DRAM synchronizes itself with
the CPU’s bus. Until recently, SDRAM was
the memory standard. When looking at
SDRAM - The number following “PC” is telling you the speed of the system’s
front side bus. (example: The PC100 SDRAM
is designed for systems equipped with a 100 MHz front side bus.)
2.
DDR-SDRAM – Double
Data Rate Synchronous Dynamic Random-Access Memory
·
This is a type of SDRAM that supports data transfers on both edges of
each clock cycle (note: the rising and falling edges), which effectively
doubles the memory chip’s data throughput. DDR-SDRAM is well-suited for notebook
computers because it uses less power.
Some newer technologies that are replacing SDRAM are RDRAM, DDR-SDRAM,
which is also called SDRAM ll and DDRAM.
3.
DDR2 SDRAM –
Double Data Rate 2 Synchronous Dynamic Random-Access Memory
·
DDR2-SDRAM offers new features and functions that help enable a higher
clock and data rate operations, DDR2 SDRAM is a step up from DDR-SDRAM. DDR2-SDRAM memory is incompatible with the
current DDR-SDRAM memory slots. It also can
transfer 64 bits of data twice every clock cycle.
4.
DDR2 SDRAM –
Double Data Rate 2 Synchronous Dynamic Random-Access Memory
·
This is the third generation of DDR-SDRAM, as you can imagine there
have been many improvements, including reduced power consumption, a double
pre-fetch buffer, and it also offers more bandwidth because of its increased
clock rate.

Laptop/Notebook Memory is Different (SO
DIMM)
You will notice that most notebook/laptop manufacturers are commonly
using the SO DIMM (Small Outline DIMM) memory modules, which are just smaller
versions of the DIMM modules that are being used in desktop PC’s. The differences in notebook RAM to desktop
RAM is noticeable by it’s size difference and its pin configuration. For instance, a full sized DIMM has 100, 168,
184, 240 pins and is most commonly 4.5 to 5 inches in length. In contrast, a SO DIMM has 72, 100, 144, 200
pins and is considerably smaller – 2.5 to 3 inches.