How to Make Use of System Memory
Computer system memory is one of the most important upgrades you can make. Data stored in RAM is much more accessible to your processor than data sitting on your hard drive, so having more memory makes your computer feel faster because its not having to wait for data.
What Does DDR2 Look Like?
DDR2 memory modules come in two main formats, one for desktop computers and the other for laptop computers. While electrically identical, they are physically very different and do not fit in the same slots at all. Both PCBs are the same height, but the modules do differ in length due to the smaller size of notebook motherboards. DDR2 and DDR3 DIMMs are the same size and have the same pin count, but they are notched differently so that you cannot fit the wrong kind of RAM in a motherboard.
- DIMMS: Desktop DDR2 memory comes in standard packages 133 mm long with 240 pins.
- SO-DIMMS: Laptop DDR2 memory packages have the same 240 pins as their bigger siblings, but in a much smaller 67 mm package.
How Does DDR2 Work?
The key to understanding how DDR2 works is less about how the data stores in the memory module, and more about how the data transfers across the memory bus to the CPU. Where the older single rate SDRAMs only transmitted a single bit of data on each tick of the clock, DDR memory transmits two bits of data, one on each of the rising and falling edge of the clock. DDR2 doubles that to two bits on each edge of the clock. When looking for DDR2 you have to know how to read the numbers:
- PC2-8500: This means that it is DDR2 with a maximum transfer rate of 8533 Megabytes per second.
- DDR2-1066: This tells you the bus speed of the connection, which is 1066 MHz.
- 8 GB: This refers to the amount of RAM on the module and is a measure of its working capacity.
Does Memory Matter?
Random Access Memory, or RAM, is one of the most important components of any computer. In an office analogy, its the desk you work on, while the hard drive is the filing cabinet. The more RAM you have, the more things you can have open at the same time. The progression from DDR, to DDR2, and then to DDR3 was not only about increasing the transfer rate for better performance, but also to make larger amounts of memory more practical. You cant use 8 GB memory modules with single data rate memory because it cant transfer that much data fast enough to make it useful; DDR2 and DDR3 can.
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