<P> This variance is designed to prevent coupling of memory and controllers of different DDR generations due to electrical incompatibility . DDR SO - DIMMs operate at 2.5 V while DDR2 SO - DIMMs operate at 1.8 V . </P> <P> These modules, while using the same physical layout, may differ in the specified voltage - 1.5 or 1.35 volts . The lower voltage modules are sometimes, but not always, identified as DDR3L - see also DDR3 SDRAM . Low voltage modules are compatible with high voltage mainboards, but not vice versa . There are some exceptions to that rule however (see reviews at https://www.newegg.com/global/fr/Product/Product.aspx?Item=N82E16820231692) </P> <P> 200 - and 204 - pin SO - DIMMs are 67.6 mm (2.66 inches) long and 31.75 mm (1.250 inches) wide, with a maximum total depth of 3.8 mm (0.15 inches). </P> <P> SO - DIMMs are more or less equal in power and voltage rating to DIMMs, and despite the smaller size of memory modules, SO - DIMM technology does not mandate lower performance compared to larger DIMMs . For example, DDR3 SO - DIMMs provide clock speeds such as 533 MHz (1066 MT / s, PC3 - 8500), CAS latencies such as 7, and higher capacities such as 4 GB per module . </P>

How many pins does a ddr3 so dimm have