Very strange fps limit issue

[eraser34]

Are you sure that the GPU isn't overheating by trying to run at a higher frame rate? In such a situation it will lower the clock speed.

Yup, the temps are fine, under 60 for both gpu and cpu. Other graphic intensive games like witcher 3 or gta5 work fine. 3dmark benchmarks work fine as well.
Also, to re-iterate, selecting fps limit 60 or none and clicking apply immediately drops my core clock speed by half.