"The artifact occurs when the video feed sent to the device isn't in sync with the display's refresh, be it due to non-matching refresh rates, or simply lack of sync between the two. During video motion, screen tearing creates a torn look as edges of objects (such as a wall or a tree) fail to line up" - from wikipedia
The ways to prevent video tearing are dependent on the technology of the display device and video card, the software in use, and the nature of the material being shown. The most common solution is to use multiple buffering.
Most systems will use this function along with one or both of these two methods:
Vertical synchronization is an option found in most systems, wherein the video card is prevented from doing anything visible to the display memory until after the monitor has finished its current refresh cycle.
During the vertical blanking interval, the driver would order the video card to either rapidly copy the off-screen graphics area into the active display area (double buffering), or treat both memory areas as displayable, and simply switch back and forth between them (page flipping).
Some graphics systems support a function wherein the software can perform its memory accesses so that they stay at the same time point relative to the display hardware's refresh cycle. In this case, the software would write to the areas of the display that have just been updated, staying just behind the monitor's active refresh point. This allows for copy routines or rendering engines which have a somewhat unpredictable throughput, as long as the rendering engine is capable of "catching up" with the monitor's active refresh point when it falls behind.
Alternatively, the software could instead stay just ahead of the active refresh point. Depending on how far ahead one chooses to stay, this method may demand code that copies or renders the display at a fixed, constant speed. Too much latency would cause the monitor to overtake the software on occasion, leading to rendering artifacts, tearing, etc.
Demo software on classic systems such as the Commodore 64 and ZX Spectrum frequently exploited these techniques, owing to the predictable nature of their respective video systems, to achieve effects that might otherwise be impossible.
Note: These are quotes are from this page in wikipedia: Screen tearing - Wikipedia, the free encyclopedia
If it is not screen tearing, then try lowering your settings on the game, hope this helps!