Memory Chip Compatibility

Random access memory modules

Memory chips, or random access memory (RAM) modules, consist of millions of electrical switches that represent the data the processor needs to run software. Manufacturers design computers to be compatible with only certain types of RAM.

Types

As of 2010, most new PC and Mac computers utilize either DDR SDRAM, DDR2 SDRAM or DDR3 SDRAM. These modules insert into memory slots located on computer motherboards. A given slot has different physical dimensions depending on which type of memory it uses. As such, the chips are not interchangeable.

Configuration

The motherboard limits the amount of RAM that can be installed on a given system. It does this in two ways. First, it limits the number of RAM banks. A given bank can consist of multiple slots that must be filled in order for the system to work. In addition, a bank can only support chips of a specific memory capacity.

Considerations

Each type of DDR comes in a range of different speeds. In most cases, a faster chip will work in a motherboard designed for a slower chip, provided the memory architecture is the same. For example, a DDR3 chip running at 8533 megabytes per second (MB/s) will usually work in a slot designed for a 6400 MB/s DDR3 chip, but it will not work in a slot designed for a 6400 MB/s DDR2 chip.

References

• "How Computers Work;" Ron White; 2008
• DDR Memory RAM: Identify RAM DDR DDR2 DDR3 Modules
• Computer Memory Upgrade: Maximum Memory, Standard Memory and Slots
• Crucial: Memory speeds and compatibility

Resources

• PC World: How to Upgrade Your PC's RAM
• Pacbell.net: What kind of memory do I have? What kind of RAM do I need?