Modern CPUs with integrated memory controllers are increasingly insensitive to memory performance. Put simply, when you have bandwidth to burn, a gigabyte here or there isn't going to hurt. Nevertheless, fast memory can help you get the most out of your CPU when overclocking. Moreover, stable memory makes for a happier system when performing all manner of tweaks.

Bandwidth
SiSoft Sandra: Gigabytes per second, bigger is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 16.76GB/s
OCZ Platinum 1,600MHz @ 1,333MHz 17.65GB/s
AData Extreme 2,000MHz @ 1,333MHz 17.23GB/s

Latency
SiSoft Sandra: Nanoseconds, lower is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 78ns
OCZ Platinum 1,600MHz @ 1,333MHz 69ns
AData Extreme 2,000MHz @ 1,333MHz 59ns

3D rendering
Cinebench R10: Time in seconds, lower is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 50s
OCZ Platinum 1,600MHz @ 1,333MHz 50s
AData Extreme 2,000MHz @ 1,333MHz 49s

Gaming
World in Conflict: Frames per second, lower is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 58fps
OCZ Platinum 1,600MHz @ 1,333MHz 61fps
AData Extreme 2,000MHz @ 1,333MHz 59fps

Peak power consumption
Total system power: Watts, lower is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 200W
OCZ Platinum 1,600MHz @ 1,333MHz 200W
AData Extreme 2,000MHz @ 1,333MHz 200W

Overclocking
Maximum overclock: MHz, higher is better
G.Skill Eco 1.35V 1,600MHz 4GB @ 1,333MHz 2,000MHz
OCZ Platinum 1,600MHz @ 1,333MHz 2,000MHz
AData Extreme 2,000MHz @ 1,333MHz 2,133MHz