Crucial 8GB Kit (2 x 4GB) DDR2-666 UDIMM

NON-ECC/Non-parity Most desktop and laptop computers take NON-ECC or Non-parity memory.

ECC/Parity ECC or parity modules look for errors in data and are most often found in servers and other mission-critical applications used by large networks and businesses.

Unbuffered Most PCs and workstations use unbuffered memory which is faster than registered memory.

Registered/Buffered Registered or buffered modules delay all information transferred to the module by one clock cycle. This type of memory is primarily used in servers.

Fully buffered Designed for next-generation servers, features an advanced memory buffer.

CL —CAS (column address strobe) latency, which is the number of clock cycles it takes before data starts to flow after a command is received. Lower CL is faster. Modules with different CL can be mixed on a system, but the system will only run at the highest (slowest) CL.

Component configuration —(For example: 64Meg x 64) Indicates the size of the memory chip components on the module.

Voltage For example 2.6V. Indicates the power used by the module. The lower the better.

Check the glossary and knowledgebase for more detailed definitions.