I would expect to see 10-15c. over ambient at idle.
I suspect you are a bit high.
Check that your case has sufficient intake to feed the cooler.
Also check that you have mounted the cooler level.
Pushpins need to be pushed down on diagonal pairs at the same time to get the cooler level.
Actually, you need do nothing.
75-85c. under stress is ok.
The processor will slow down or shut off if it detects a dangerous temperature.
That is around 100c.