I had the same issue ever since I got this board, which was in September 2014 right around when the board became available. Tried all the BIOSes, did an RMA on my RAM, messed with a bunch of settings, all to no avail. I was running Windows 7, though.
Anyways, with BIOS version 3301, the problem seems to have gone away. I did manually tweak my System Agent Voltage to be higher than the default (0.88 v), disabled CPU Spread Spectrum, enabled XMP (have a 32GB Ripjaws 2400MHz kit) and manually specified a couple of voltages like Vcore.
I will say that occasionally, the system will resume from sleep when I move the mouse or hit a key but take a long time before it posts. I haven't had any of the random reboots other people have complained about on 3301 not issues with USB devices disconnecting. My understanding is that there is a new BIOS in the works to address those issues for the users that are experiencing them.
So my advice is give 3301 a try along with some of the tweaks I mentioned and see how it goes for you. And even when you think the system is frozen and not posting, give it some time and see if it recovers. I'll say that the system should resume when you move the mouse or hit a key. If it doesn't and requires you to hit the power button, then I wouldn't bother waiting as it's probably stuck and will require a power cycle.
BTW, I almost gave up and was thinking of going to the Rampage V 10 myself. Crazy if you think about it, rewarding a company that can't sort out issues with their high end products by purchasing more of their products. But Asus's designs and features are hard to beat. I still have my Rampage IV Extreme being used in a secondary machine, although ironically, I also had an issue with that board that was never resolved and required me to buy a separate NIC.