First set I've tried is pretty good so far. Had to move them from RAM slots 1+3 to 2+4 - couldn't boot past 2200 with the ram in channel A.
I wasn't expecting much out of them from a Z68 board seeing as most of you are using them on the Z77

2400mhz 10-11-11-28 1T @ 1.63v
Haven't had much time to tweak them, can probably lower the voltage a little. They are lukewarm to the touch while running Memtest86.