. Crucial 240-pin DIMMs are used in DDR3 memory for desktop computers. DDR3 is the latest generation of memory with an enhanced 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 & a socket on a larger printed circuit board. The pins on the front & 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™ & 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 1066 M Hz) & PC3-10600 (DDR3 1333 M Hz) speeds. Additional speeds will be added as the technology becomes available. To use DDR3 memory your system motherboard must have 240-pin DIMM slots & 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 & 120 pins on the back for a total of 240. 240-pin DIMMs are Approx. 5.25 inches long & 1.18 inches high though the heights can vary. While 240-pin DDR3 DIMMS 240-pin DDR2 DIMMs 184-pin DDR DIMMs & 168-pin DIMMs are Approx. the same size 240-pin DIMMs & 184-pin DIMMs have only one notch within the row of pins..