from stabby 3+ years ago
stabbyIn-game sensitivity is a multiplier. It takes the counts of movement recorded by mouse and multiplies it to determine the final distance your cursor moves.
DPI or CPI = Dots/Counts per inch. CPI basically is the number of units the mouse splits an inch into. So if you have a CPI of "1,000" your mouse records 1,000 movement units, and tells the cursor to move 1,000 pixels. So, using an in-game sensitivity of "1.0" and a CPI of "400", if you move your mouse one inch your view will move 400 pixels on your display.
If your sensitivity is too high (above 2.7128 for 1920x1080 displays), you will be unable to move your view by one pixel at a time, even with the slightest movement--this is called "pixel skipping".
Do note that higher DPI is not always better. Certain mice have "native" DPI steps which you should use. Most mice also get tracking errors at lower speeds with higher DPI's. And as was mentioned, on multimonitor displays it can cause your cursor to fly onto the other screen out of game (this can be rectified with an .exe called "CursorLock" btw).
So...use the in-game sensitivity that will allow you to use a native DPI step while keeping your in-game under 2.7128 (for other resolutions, use this to calculate the number).