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.
For Energy-Efficient memory, please be certain that your system supports 1.5v Energy Efficient memory prior to ordering. For more information please visit the Energy Efficient Memory homepage.
FBDIMM for Apple Mac Pro
Note: Because Crucial carries modules with more than one design of Apple-approved heat spreaders, your module may look slightly different from the example shown above. Because it’s designed to deliver improved performance for demanding applications, FBDIMM memory tends to run at a higher temperature when compared with other DRAM. And that stands to reason as the MacPro — running at speeds up to 3GHz — is the fastest Mac system to date.Now, upgrading the FBDIMM memory in those systems is quick, easy, and affordable. Crucial’s FBDIMM modules meet Apple’s unique standards for the MacPro systems, including a highly engineered design featuring heat spreaders that dissipate more heat faster, which allows for lower noise levels because the fans can run slower. So if you’re a Mac user who wants to maximize performance on the MacPro system, let Crucial help you find the right upgrade today. (Please note that FBDIMMS must be installed in pairs.)
Note: Because Crucial carries modules with more than one design of FBDIMM-approved heat spreaders, your module may look slightly different from the example shown above. Below are some of the other possible products you may receive when ordering this product.
Approximately 5.25 in. by 1.18 in. (133.35 mm by 30 mm)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).DDR2 240-pin fully buffered DIMMs are available in DDR2 PC2-4200 SDRAM and DDR2 PC2-5300 SDRAM.To use DDR2 memory, your system motherboard must have 240-pin DIMM slots and a DDR2-enabled chipset. A DDR2 SDRAM DIMM will not fit into a standard SDRAM DIMM socket or a DDR DIMM socket.To use fully buffered DIMMs, your server or motherboard must use FBDIMM architecture. An FBDIMM will not fit into a standard DDR2 socket, and a DDR2 module will not fit into an FBDIMM 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 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. The notch in a 240-pin fully buffered DDR2 DIMM is in a different location than the notch for regular 240-pin DDR2 modules.