Crucial
8GB 1866MHz DDR3 Registered Server Memory Module (CT8G3ERSDD8186D)

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.

Please make sure you have checked compatibility between the memory you want to purchase and the motherboard or notebook for which the memory is intended to be used. If the package is opened and the memory is not in resealable condition it cannot be returned for credit.
        
 Kingston, Crucial, OWC & Transcend memory - when not in stock can be ordered on request - takes 5-15 business days.

Check Crucial compatibility here:  https://www.crucial.com/store/advisor