Most memory would be rated at something like ddr3-1600 1.65volts, ddr3-1333 1.60volts, ddr3-1066 1.50volts. It will be different for each brand/model and speed of memory.
You have to google the memory sticks you have, find their speed/timings/voltage chart on their site. Most will tell you the max safe voltage and lowest voltage/speed the memory will work at.
Mine are kingston sticks.
My board is a gigabyte A75M-UD2H
It will vary from board to board on what settings they offer in the bios.