Amount of available storage on the module. If there are parenthesis shown – for example (2 x 4GB) – it indicates a kit of 2 or more identical modules is used to reach the Total Capacity.
Number of modules. Memory can be installed as single modules or in kits comprised of 2 or more identical modules. Each module requires its own slot for installation.
Memory spec terms
If you're not sure if a module is right for your system, use the Crucial Memory Advisor tool for a list of guaranteed compatible modules.
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.
A dual inline memory module (DIMM) consists of a number of memory components (usually black) that are attached to a printed circuit board (usually green). The gold pins on the bottom of the DIMM provide a connection between the module and a socket on a larger printed circuit board. The pins on the front and back of a DIMM are not connected to each other.
240-pin fully buffered DIMMs (FBDIMMs) are used to provide DDR2 SDRAM memory for servers and motherboards that use FBDIMM technology, as opposed to conventional registered DIMM (RDIMM) technology. DDR2 is a leading-edge generation of memory with an improved architecture that allows it to transmit data very fast. FBDIMM technology utilizes an advanced memory buffer that allows modules to be connected in series meaning that more memory modules can be connected (and thus memory density is increased) and errors at the connection points are reduced.
Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered or fully buffered modules).
To use DDR2 memory, your system motherboard must have 240-pin DIMM slots.