Im not sure about the voltage, but why you getting 12Gbs of RAM in total, if it's for gaming then it's not going to help because 4Gb is plenty enough, or if it's for high rate of multy tasking then 8Gb is plenty enough for that is well.
Also i would recommend this RAM:
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL7D-4GBRMhttp://www.newegg.com/Product/Product.aspx?Item=N82E16820231303
This RAM has better CAS LATENCY (7) wich is alot better, and also has higher speed.
If you want 8Gb then get this RAM twice and your are done.
Hope this helps :P