Overclockers Club has a few sticks of Corsair's Vengeance LPX 16GB 2800MHz DDR4 on the test bench today. Here's a quote from the full review:
Out of the box they come with 16-18-18-36 primary timings using just 1.2v to run the modules. By tweaking the applied voltage a little bit you can get the timings much tighter at the rated speed and even when running at my max overclock of 3200MHz. At this speed I was able to run the timings at 15-15-15-28 2T using over 1.4v applied to the modules.