The only ram worth buying those days: 30nm samsung ddr3-1600 CL11 1.35v.
Don't let the CL11 part fool you: those sticks cost around 45$ for 2X4 gb and overclock like hell. You can get them to 2200-2300 cl10 or 1600 cl6. The most flexible ram around.
Google them and read some reviews. Always 10/10, anywhere you look.