Lower voltage will make the memory run cooler. It is possible but hard to say if the cooler running memory will it last longer. I tend to try to choose things that run cooler and since its cheap memory why not. Also, the lower voltage should put less stress on the Sandy Bridge IMC(Integrated Memory Controller).
Anand has a good article on memory for the Sandy Bridge CPU's. Basically timing and frequency don't matter that much. If your building for playing games see the chart with Crysis and Metro on this review. They got less than 1 FPS going from DDR3-1333 to DDR3-2133. http://www.anandtech.com/show/4503/sandy-bridge-memory-...
FYI: I just bought the ASRock Z68 EXTREME4 GEN3 from newegg.
Just thought everyone might be interested that you will only get the benefit of PCI-E 3.0 with Ivy Bridge CPU. Please see note from ASRock website.
Note: To run the PCI Express 3.0 slots in Gen 3 speed, you must install the Ivy Bridge CPU which supports PCI Express 3.0. If you install the Sandy Bridge CPU, the PCI Express 3.0 slots will run only at Gen2 speed.
Also, PLX PEX8608 chip onboard for Extreme 4 gen. 3
Note: With PLX PEX8608 chip, it generates more PCI-E lanes for PCI-E devices, so that all PCI-E devices are able to work at the proper speed simultaneously!