Computer Memory

1. Random access memory (usually known by its acronym, RAM) is a type of computer data storage. Today it takes the form of integrated circuits that allow the stored data to be accessed in any order, i.e. at RANDOM. The word RAM is mostly associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off. RAM is used as 'main memory' the working area used for loading, displaying and manipulating applications and data. In most personal computers, the RAM is not an integral part of the motherboard or CPU - it comes in the easily upgraded form of modules called memory sticks or RAM sticks. These can quickly be removed and replaced should they become damaged or too small for current purposes.


RAM Modules


2. This contrasts with storage mechanisms such as tapes, magnetic discs or Hard Drives and optical discs, which rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than the data transfer, and the retrieval time varies depending on the physical location of the next item. Data is not lost when the power is turned off on these types of devices. Do not get RAM confused with the Hard Drive, they are two separate devices inside your computer. The Hard Drive is your storage device whose capacity is also measured in Megabytes and Gigabytes. .

hard drive

Hard Drive

hard drive

Hard Drive with cover removed


3. RAM Size or capacity - Today, the most common RAM modules are 2GB, 4GB, and 8GB.

4. RAM types: RAM chips come in a variety of shapes and sizes.


DDR3 240-pin DIMM

240-pin DIMMs are used in the newest and fastest DDR3 memory desktop computers. DDR3 is the latest generation of memory with an improved architecture that allows it to transmit data more quickly. Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered or Fully Buffered modules). Standard DDR3 240-pin DIMMs are currently available in DDR3 PC3-8500 SDRAM and DDR3 PC3-12800 SDRAM. Additional speeds will be added as the technology becomes available. To use DDR3 memory, your system motherboard must have 240-pin DIMM slots and a DDR3-enabled chipset. A DDR3 SDRAM DIMM will not fit into a standard DDR2 DIMM socket or a DDR DIMM socket. The number of black components on a 240-pin DIMM can vary, but it always has 120 pins on the front and 120 pins on the back, for a total of 240. 240-pin DIMMs are approximately 5.25 inches long and 1.18 inches high, though the heights can vary. While 240-pin DDR3 DIMMS, 240-pin DDR2 DIMMs, 184-pin DDR DIMMs, and 168-pin DIMMs are approximately the same size, 240-pin DIMMs and 184-pin DIMMs have only one notch within the row of pins.


DDR 2 240Pin

Used in the newest and fastest Computers. 133.350 x 29.970 mm or 5.25" by 1.18". To use DDR2 memory, your system motherboard must have 240-pin DIMM slots and a DDR2-enabled chipset.


DDR 184 Pin


SDRAM 168-pin - Used in older desktop computers.


SODIMM 72-pin - Used on Laptop computers.


SODIMM 144-pin - Used in Laptop computers.


SODIMM 200-pin - DDR memory used in newer Laptop computers.

5. Dual-channel architecture describes a technology that effectively doubles data output from RAM to the Memory Controller. Dual channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from RAM to the CPU. In order to achieve this, the memory modules must be installed into matching banks, which are usually colour coded on the Motherboard.


Identical modules MUST be used, Modules rated at different speeds and size will not run in dual channel mode. Some motherboards have compatibility issues with certain brands or models of modules when attempting to use them in dual channel mode. For this reason it is strongly advised to use identical pairs of memory modules and most memory manufacturers now sell kits of matched pair DIMMs. Several motherboard manufacturers only support configurations where a "matched pair" of modules are used. Dual-channel architecture is a technology embraced by motherboard manufactures and does not apply to memory modules. In other words, any matched pair of memory modules may support single and dual-channel operation, provided the motherboard supports this architecture. Consult your motherboard manual on how to install the memory modules for dual channel. 

6. Notebooks:

Nowadays almost all notebook computers allow you to expand their RAM memory capacity. This is possible because they use memory modules just like desktops, but in a different form factor, called SO-DIMM (Small Outline Dual in Line Memory Module). So, the memory modules used on desktops cannot be used in notebooks and vice-versa. Notebook SODIMMS are show above.

7. If you have a Dell, Compaq, Toshiba, Gateway, HP, or other OEM computer! Know in advance; that these OEM computers require very specific memory part numbers or the upgrade will fail. Only buy and install part numbers listed by the memory maker as being for your specific model number. You don't need to buy your upgrade from the computer maker since they charge very high prices. But make very sure that the memory part number you buy is listed for your exact model number.

8. Installing RAM.




9. RAM limitations. 32 bit operating systems will not recognize 4GB of RAM. Click HERE to find out why.


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