I am going to just not trust speedfan in this case.
With software that can monitor many boards, sometimes the misread things. Temperatures do not tend to go DOWN under load(while some may from fans speeding up, but not that much).
Can you ensure your cooler pins have been fully inserted. If they did not lock in on the other side of the board the cooling performance will not be good.
If you plan to try to remount the cooler, you will have to get thermal paste and clean off the old stuff.