What is Dual-Voltage RAM?
In the past, most DDR3 memory voltage ranged from 1.5 - 1.65v. More recently, dual 1.35/1.5 voltage modules have become available. While the lower voltage memory has some advantages over high voltage (namely lower power consumption), your system must support it in order to realize the benefits.
Which is better; 1.35V/1.5V or 1.5V?
Generally, lower voltage is considered better, as it consumes less power and in turn, may generate less heat. However, it is important to note that the overall system must support DDR3L (1.35V low voltage) to enable the module to run at 1.35V. If the system does not support DDR3L (1.35V low voltage), the module will run at 1.5V.
Which one should I buy; 1.35V/1.5V or 1.5V?
Purchase whichever of memory your system supports, but keep in mind the dual-voltage module will run only run at 1.35V if your system supports that voltage, otherwise you won't get the benefit of the lower voltage and the memory will run at 1.5V.
Will the dual voltage 1.35V/1.5V parts work with my original memory?
If your original installed memory is 1.5V and you are adding a
dual-voltage 1.35V/1.5V module to an open DIMM slot, the dual-voltage
module will operate at 1.5V, not 1.35V. In order to run at 1.35V, all
installed memory modules must be dual-voltage 1.35V/1.5V and the system
must support DDR3L (1.35V low voltage) to enable the module to run at
1.35V.