Hi raydEx -
When you displace a Mesh using the Materials the original bounds of the object are not affected. Which means that the render is attempting to draw the object to your displacement, but also trying to respect the original bounds of the object. Too much in any one direction can lead to a flickering that you are describing in which the object is both being rendered and out of bounds at the same time.
You will need to go into the mesh details panel in the level viewport and increase the bounds scale until the flickering stops.
Thank You
Eric Ketchum