I have narrowed down my new mobo upgrade to either an ASRock Extreme 4 or 6. It will be mated with a 4790K CPU and 16 GB of existing G.SKILL TridentX Series 16GB (2 x 8GB) DDR3 2400. The 4 is consequentially less expensive and seems to have more to offer. My primary criteria are speed and reliability. Is there any advantage with respect to speed and stability, including posting, for spending a lot more on the 6? In fact, I am not sure I understand why the 6 is more expensive but I am willing to buy it if it has performance advantages.