you will notice if benching or doing certain ram heavy tasks. is the main purpose of this rig for gaming? if so, dont bother with the higher speed ram. but then again, if its just a gaming rig, you dont need an i7 either. Read up here this is a good article.http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3/1
Its main use is for programming. I am a Computer Science major and my school requires us to work with engineers so I run some heavy engineer programs like MatLab and Solid Works, I'll also be doing my own programs written by me and my team, its why I went with the i7, handles the larger programs and MatLab better.
I will also game on it, just not all that much, BF3, Planeside 2, other steam games, diablo 3.
With running heavy programs will that speedier ram help out?