These Crucial 240-pin DIMMs use DDR3 memory rated at 1600 MHz 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.
Column Address Strobe (CAS) latency, or CL, is the number of clock cycles it takes before data starts to flow after a memory access 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.