To add to this, but not to take away from eva's blazing speeds I wanted to share a little bit I've been doing with these Kingstons HyperX by tightening the timings to match the specs of Mushkin Redline rated at 1600 cas 6 timings.
The Mushkins will run at 6-7-6-18 1.65v, so far I've been reluctant to use them for super pi or WPrime benchmarks because for some reason they perform a second worse on each test in comparison to some Cruicial Value ram I overclocked from 1066MHz to 1600Mhz 8-8-8-21. That seems sort of odd, but even more strange is that EVERY application on my machine functioned the opposite way. Things were much more snappy. Higher CPU scores in vantage and a minor increase in frame rates. The only problem I'm finding with the Redlines is that they are unreliable... 4 days of owning the sticks and they are exhibiting signs of degradation. I saw the Kingston HyperX on newegg.com for $240.00 so I had to buy.
Here's what happened when I underclocked and tightened
My system is running at 4.2GHz 1.4000 Vcore in bios 1.408V from the multimeter, QPI @ 1.37V, DRAM @ 1.65V, Nominal VTT PWM frequency, -30% DRAM PWM frequency. Like it says in my MSN conversation I've NEVER had my i7 complete a 32M run. Everything else would be rock solid, but the XS Mod would always crash at around loop 15-18. Motherboard used was my DFI x58 T3eH8. Like I said earlier this is to show how flexible this ram can be and I am amazed. I hope this adds to the info eva has been able to provide so far.