Depends on your chipset mainly. Older DDR3 memory was specced at 1.65volts, newer intel systems like to see 1.5volts as the maximum safe voltage since the memory controller moved to the CPU.
Safest thing to do is stick the QVL or HCL of your given motherboard. (Qualified Vendor List, Hardware Compatibility List)
1.5 volts +/- 5% has always been the JEDEC standard for DDR3. Performance modules typically use 1.6 or 1.65 volts to achieve stability at higher data rates. Performance DDR3 dominated the market because mainstream DDR3 wasn't clearly superior to DDR2 and didn't justify its price premium. Since DDR3 has now been around for quite some time, newer modules fabricated on newer processes do not need as much voltage to achieve stable operation at the same data rate.
For example, 90nm DDR3-1600 would have been considered exotic in 2008 and would have most likely required 1.65 volts. In 2011 30-40nm DDR3-1600 would be considered mainstream and would have required 1.65 volts. In 2014, 20nm DDR3L-1600 can run at 1.35 volts.