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Type of System Memory

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What is Computer Memory?

The memory of a computer is a temporary data storage, it is compared to a hard drive that stores data for read/ write access operation but the difference is that the content inside the memory will only be available till the computer is powered on and when you turn it off or restart your system all its content will be lost. Before a program can be run the program should be loaded from your drive to the system memory for faster access when needed by the processor, this also allow the processor for direct access to the program that was loaded.

Low on system memory will slow down your PC and you may notice that your processor is constantly accessing your drive by just looking at the HDD LED indicator at the front panel of your desktop computer. In windows to execute a program, the program needs to be loaded first in memory. Windows would let you multi-task running multiple applications at the same time, due to the different applications loaded in memory chances are they would not all fit in the available memory unless you have a lots of installed memory. Windows will use its virtual Memory simulating the Random Access Memory (RAM) pretending there are more RAM in your system but here it uses a file to simulate your RAM, it does this by moving data from real memory to a file in your hard drive, because of this windows will be able to address more memory than what is physically installed on your system. The catch with this virtual memory is that it really slows down your system because the processor accesses the data constantly from the hard drive instead of directly accessing the data from the system memory considering that hard disk transfer rate is only approximately 126mb/s compared to DDR-266 memory which is 266Mbp/s or with DDR3-1333 with 1333Mbp/s, so this really slows down your computer and the situation will be aggravated when you have a slow processor, you may take a coffee break first while waiting for the program to load :-).

When upgrading your computer memory always take note that memory types are not backward or forward compatible with other computer memory type, for example DDR2 is not compatible with DDR or DDR3 or vice versa but same type with different speed are cross compatible. Example will be using two memories with DDR2-533 and DDR2-667 can be used but always the slowest DDR type such as the DDR2-533 will be used by the system. The DDR2-667 will be downgraded or adjust its speed to DDR2-533 to run the system properly.

Upgrading your system memory does not necessarily speed up your computer but you also have to consider other factor such as your CPU speed, hard drive, the program application you’re using and the operating system installed on your computer, all of this contributes to the overall speed of your computer system. 3Gb and above of system memory should use 64bit operating system to take advantage of the additional memory otherwise if 32bit operating system is used only 3Gb of memory will be used and the excess above 3Gb will be strip, but before you can install 64bit operating system make sure your processor support 64bit architecture.

Having a high speed processor with low on memory installed will make your system slow. Considering enough memory of at least 1GB or more of system memory is always a good consideration when building your computer especially when you are aiming for a pc gaming setup. Below is a table indicating different types of memory with its basic specifications.

Types of Computer Memory

Memory Speed Grade Bandwidth Number of Pins
DDR-266 266Mbps 2100MB/s 184-pin
DDR-333 333Mbps 2700MB/s 184-pin
DDR-400 400Mbps 3200MB/s 184-pin
DDR2-533 533Mbps 4300MB/s 240-pin
DDR2-667 667Mbps 5300MB/s 240-pin
DDR2-800 800Mbps 6400MB/s 240-pin
DDR3-1066 1066Mbps 8500MB/s 240-pin
DDR3-1333 1333Mbps 10600MB/s 240-pin

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