If you really want to compare the memory performance in games, you have to pick games where the CPU is easily a bottleneck. GTA V for example. Not BF4... And, using a weak CPU instead also helps. So, an i3 rather than an i7.
Hmm after my asus sabertooth died with 4.4ghz 2600k im back at my i7 920 at 2.8ghz and gtx970 in a pci-e 2 slot i can still game at the same high settings. Or normal on 5760x1200 3screen nvidia surround 60fps. So i didnt think gta v is that hard on cpu