Crucial 240-pin DIMMs are used in DDR3 memory for desktop computers. DDR3 is the latest generation of memory with an improved architecture that allows it to transmit data more quickly.

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.

Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered or Fully Buffered modules). (The Ballistix™ and Ballistix Tracer™ high-performance memory do not come in 72-bit or registered modules.) Standard DDR3 240-pin DIMMs are currently available in PC3-8500 (DDR3 1066MHz) and PC3-10600 (DDR3 1333MHz) speeds. 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. This is because 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.