Make sure you always use high end DDR3 memory otherwise you system will bottle neck the latency is the most important factor in any system commands.
No matter how fast your CPU or GPU is, the memory is where it will bottle neck if you have shitty store bought memory.
For true video editing and encoding always use DDR3 memory that is no higher than Cas Latency 7.
Cas Latency 8, 9, 10 are to slow in giving commands to high bandwidth CPU and GPU through put.
Here is great memory
http://www.newegg.com/Product/Produc...82E16820145327
Dont fall for the cool looking ram modules.