With that said I wouldnt bother with buying a temp gauge. If the HS is cool to the touch under load with a fan, then its cooling it. And if its getting hot with no fan, it is clearly pulling the heat up. I think your sensors got fried and are mis-reporting. And the fact its stable, rock stable, is proof that there are no problems. Save your money on the temp gauge, reseat the HS again and let it be.