I think it's safe to say it's as good as you're going to get for air cooling.i have this cooler Noctua NH-D15, is it good enogh for the r9 5950x
yes it is fine
I think it's safe to say it's as good as you're going to get for air cooling.
The next thing is make sure your case is well ventilated. No air cooler will work well if just recirculating the warm air from the CPU and GPU.