TestFreaks posted a review on the Kingston HyperX DDR3 4gig Memory Kit 1600Mhz KHX1600C8D3K2/4GX 1.65V A quote from the article:

I've got a 4gig set of Kingston HyperX DDR3 ram that runs at 1600Mhz and has the low voltage requirements of the Corei5 system. In my time with this set of ram I've found that it easily overclocks to almost 2000Mhz and it will even run at a lower latency. I put it in my system with my Corei5 750 CPU and ran a bunch of tests to see just how well it performs, so read on to learn more

>> Kingston HyperX DDR3 4gig Memory Kit 1600Mhz KHX1600C8D3K2/4GX 1.65V Review