Know your vsync

[Codex]

VSync doesn't work that way. Vsync (either set in game or the graphics card driver) ensures that before the next frame is drawn on your display, your monitor has completed the current draw call. Only then will the next draw call be made.

You can still have odd numbered frame rates or lower frame rates than what you've set your refresh rate on your monitor (i.e. most LCDs max at 60 Hz). It just means your PC isn't processing the game engine fast enough to get the max frame out.

Say for example the game engine is pumping out frames at 43 fps and your monitor's refresh is set to 60 Hz, with Vsync on you wont (or shouldn't) see tearing as the game or graphics card driver wont display a frame until the current draw call on the monitor is done. What you may see however is a slide show if the frame rate drops below 30fps