Hi, I have an issue while playing Grand Theft Auto 5 on my PC. (Specs are below)

i5 4670K
GTX 1070 (8gb of VRAM)
16GB Ram

http://imgur.com/a/r1lHy  This picture shows the Usage and temperature of components, look at the numbers ON THE YELLOW LINE. Those are the numbers that show while playing the game. My problem is the framerate (it's 40-60 FPS but not shown in the picture) It seems as if it's bottle necked but I don't know why that would be as every forum has said that wouldn't be the case. Any idea what might cause this?