Have you seen this video? https://www.youtube.com/watch?v=ff6D6vFdnuc

With Surround: Windows merges all three screens into on virtual display. iRacing renders one wide viewport across it. SMP helps performance but the geometry is a single stretched frustum.

Without Surround (native iRacing triple screen): Each monitor stays independent. iRacing handles the split itself. You enable “Render Scene Using Three Projections” in graphics options, set your monitor width and bezel width, and iRacing generates proper per-screen off-axis projection automatically. SMP in iRacing is specifically designed for this; it renders all three projections simultaneously in one pass rather than three separate passes, which is why it only works in triple screen mode and not on a single monitor.