Normaly (no variable refresh rate display), you can request an Immediate present interval, and the video card will display your frame as fast as possible without waiting. This causes tearing.
In D3D9, this was done by using D3DPRESENT_INTERVAL_IMMEDIATE, and drawing with tearing is also possible in other graphics APIs (OpenGL, D3D12, etc)
But if you have a variable refresh rate display (such as G-Sync), the meaning of “presenting immediately” changes. The driver interprets each present call as if it is a full complete frame, and wants to wait for the display hardware to be ready for another frame.
Is it possible to get the “Immediate” behavior where there is zero delay with tearing, and not the “variable-refresh rate” behavior?