Make sure the cooler is porperly mounted. Intels like to pop up at one of the corners for example.
Make sure the plastic seal on the cooler was removed before being mounted on the CPU.
Make sure Thermal compound was applied if it was not pre-applied. New compound will be needed if the cooler is loose or removed.
80+C idle on a liquid cooler at idle usually means no flow. Make sure the pump is actually working. If it does, either the pump has died, stalled or coolant got out and there is nothing left to cool the CPU with.
It was mentioned above to reset your CMOS.. but I did not see you say you did. Follow the steps for your board to do that.
IF you have, have your went back through your BIOs settings, reset to Default ? IF all of this has been done, I also think you need to address your cooler, dust in the fan, fins or failure.
if you ran a bad oc you may have corrupted your o.s so try a repair install of windows. (keep your files but it will remove all installed applications)
also when you reset everything. did you re enable things like xmp?