If you're using f.lux make sure it's on safe mode, By right clicking and click "Safe Mode". I found this problem just now and it actually works, no more input lag, no more stuttering.
EDIT:
OS:windows 10
CPU: i7 4790k
GPU:GTX 970
RAM: 16GB
games i tried:
H1Z1
CSGO
OSU
DOTA
LEAGUE OF LEGENDS
EDIT:
OS:windows 10
CPU: i7 4790k
GPU:GTX 970
RAM: 16GB
games i tried:
H1Z1
CSGO
OSU
DOTA
LEAGUE OF LEGENDS