G.SKILL Ripjaws X Series 16GB (4 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Low Voltage Desktop Memory Model F3-12800CL9Q-16GBXM. It is a low voltage memory. Using AII suite... how much were you able to overclock to and remain stable?
You should be able to use the kit, to answer your other question each kit has a different amount of headroom. With all 4 slots used your going to have to experiment with different mem/cpu voltages and timings to get it as solid as possible. 1866 should be doable