The important thing is to not use memory with voltage over 1.65v as this could damage the memory controller. otehrwise you should be fine. It ain't usually recommended to put diff manufacturers of memory on teh same board simply because they mat be incompatible, but nowadays boards can cope better with this. you will soon find out if it boots up or not.
In tehory running RAM at 1.5v will increase your life of the CPU, but we are talking something liek 20 to 25...