lower it in increments of .005 voltage to be on the safe side. It might be your mobo just needing extra juice, but More voltage=More Heat. If you can lower voltages, you decrease heat AND lengthen its lifespan.
The range I would shoot for is 1.3-1.385 for 4.5 GHz. DEF stay below 1.4...for me that meant a 10C increase.
If all else fails, A temp limit would be 80C under unrealistic loads, and you should be good for daily 24/7 use.
I started at 4.5 GHz @ 1.35 VCore, try from there.