This happened to me too, thought my board was toast, It turned out that my Ram Kingston HyperX 2133 DDR3L doesn't yet play well since the flash. Mr. Fox has suggested it might have to do with the new SPD tables on newer sticks of Corsair and Kingston Ram vs. the 2+ year old version (that seemingly works as PnP, and the newer stuck doesn't unless reflashed with Typhoon Burner)
If this is the case & and you still have your factory nanya ram around, just put one stick of that in with your others and it should post. from there you can put in manual Ram timings. I read on another forum (http://tinyurl.com/jpwoakr) that M18x r2 doesn't seem to play well with the tCWL being over 9, at least that is something else to look into.
Don't take this as the solution just yet. I'm still trying to get mine working..