SODIMM

SODIMM or SO-DIMM - smaller than a conventional DIMM. A type of computer memory often found associated with laptop computers. SO-DIMMs are often used in systems that have limited space, which include laptops, notebooks, small-footprint personal computers such as those based on Mini-ITX motherboards, high-end upgradable office printers, and networking hardware such as routers and NAS devices.

DDR - Double Data Rate (DDR) or two per clock cycle

DDR3-1600 and PC3-12800 are the same clock speed. This one is 1600 megatransfers per second and 12800 is bandwidth in megabytes per second for the same ram which is the same speed.

11 - 13 - C3 - refers to the RAM timing values. The first number is the CAS latency, or the number of clock cycles it takes, in this case a CAS latency of 11 also expressed sometimes as 11 CL

RAM with the following on the label: 2GB 1Rx16 PC3L - 12800S - 11 - 13 - C3

Breaks down like this:

• 2GB memory
• PC3L indicates DDR3 as well as the special L in the case indicating low voltage RAM 1.25v
• 12800S is the same as 1600 MT (two ways to express RAM of the same speed)
• 11 -13 - C3 has a CAS latency of 11 (or 11 CL) with 13 as the SPD (Serial Presence Detect) and C3 being a company version number designation.

It is not good to mix RAM of different CAS timings. This becomes particularly difficult when a laptop has its first module soldered to the mainboard and an expansion module. The owner has no choice but to determine exactly what is built on and try to match the speed, latency, and voltage.

Upgrade Checklist

• Consider ram clock speed. A PC3-12800 SO-DIMM has a clock speed of 1600 MHz
• Consider voltage. A PC3 SO-DIMM is 1.5V while a PC3L is 1.25V.
• Consider CAS Latency. Ram with a CL11 latency wont mix well with ram of a different latency such as CL15 (or CAS 11 and CAS 15)