That's a lot of heat for such a low voltage, I presume we're talking about 3.0GHz, is that correct?
Have you checked to see that your cooler is still firmly attached, those push pins can let go.
1.28v is pretty high for 3.0GHz too which will elevate your temps, I'm using 1.24375v to get 3.0GHz, I just happen to have it running on a test too, lol