If in doubt, reset to default before going further.
Make sure to disable auto oc features. I personally leave on "Cool & Quiet, and C1", leaving these on allows my system to run nice and cool while I'm not using it (I'm no longer worried about unnecessary wear on my cpu), I've seen no performance difference since using these settings, but, what ever.
I'd suggest starting by setting your cpu voltage to manually run at base value (I've got a GB mobo, for this I had to set it to 0.000), not sure about yours. Next, Open up your LLC "Load Line Calibration" to extreme. I personally found that by doing this, I can get a stable OC without having to set my voltage to insane levels.
From there slowly increase your multiplier, run prime95 atleast 20 min at first, but, you'll want more like an hour once you get higher (ex. at 4.0 I ran prime95 for 20 min, at 4.2 45 min, at 4.4 and 4.5 at least a hour), if you fail prime95 than it's time to even up your voltage slowly, or decrease your multiplier. The end goal would be a nice stable oc that will prim95 for at least 3 hours.
It's a pain in the butt, but, just make sure to take the steps slowly, and you should be ok.