81c temperature for the 6000 series GPU card is well below it maximum operating temperature of 110c.
I wouldn't worry about it unless it goes above 100c.
EDIT: If you were using a lower Resolution Monitor like 1080P before and decided to upgrade it to a higher Resolution Monitor then the GPU needs to use more power to run at the higher Resolution. Thus the higher temps.
Only ways to lower temps besides fan and air config are
1) Repasting GPU
2) Putting GPU on liquid metal (dangerous)
3) Waterblocking GPU (dangerous)
6) Lowering power limit.
To be fair there is also big difference between 81 degrees on edge or 81 degrees on hotspot (junction)
Juction rated temps are up to 110 degrees (even though over 100 aren't favourable).
And there is up to 25 degrees difference between edge and junction temps.