Probably but ask yourself what are the pros and cons of doing this.
Pro - Hitting that 4.0GHz mark.
Con - Risking a heating problem and damaging the CPU for a 2.5% increase in power.
So for instance if you were doing video encoding and a task normally took you 60 seconds to complete at 3.9GHz, you would now complete it in 58.5 seconds. Is it worth it to you to shave 1.5 seconds from that task? If so go for it. If not, then its probably not worth any headache for such a small gain.