You are treading in OC territory with XMP.
On two of my comps, XMP does not kick the ram voltage up to spec and I had to do it manually, it is definitely needed.
Look at the last number in the XMP sequence (it'll be something like 1.35), that should be ram voltage. you'll probably need to set that manually.
Still have instability?
Things don't always run as fast as advertised. Corsair is known to lie about their high end Ram speeds and not warranty them when called on it. Other mfgr's may as well.
If you don't want to get in a pissing match with a RAM mfgr, slow it down where it says ram frequency. Shouldn't take more than a step or 3. Once you can run AIDA64 stress test on the memory and it performs, take it down 1 more click so you aren't on the bleeding edge.