NVIDIA manages to make this possible by introducing a new additional "Last Rendered Buffer" that sits right between the Front and Back buffer. Initially, the GPU renders a frame into the Back buffer, and then the frame in the Back buffer is immediately moved to the Last Rendered Buffer. After this, the GPU renders the next frame into the back buffer and while this happens, the frame in the last rendered buffer is moved to the front buffer. Now the Last Rendered buffer waits for the next frame, from the back buffer. In the meantime, the Front buffer undergoes the scanning process, and the image is then sent to the monitor. Now, the Last Rendered Buffer sends the frame to the front buffer for scanning and displaying it on the monitor. As a result of this, the game engine is not slowed down as the Back buffer is always available for the GPU to render to, and you don't experience screen tearing as there's always a frame store in the front buffer for the scan, thanks to the inclusion of Last Rendered buffer.
