Good Morning everyone,
as the image shows, it happened when i run the scene (also happened when i build and run), that white box suddenly appear and dissapear. my GPU still new, (i dont think its my GPU).
is anyone out there facing the same problem with me? or anyone who have a solution for this? 
Does that white box actually exist? If so, that’s a Z-fighting problem: when faces of two objects are at the same distance from the camera, parts of them overlap randomly because the depth buffer has almost identical values. If this is the case, move one of them a little ahead. On the other hand, if the white box isn’t an actual game object, your GPU may have compatibility issues with the current Unity version - maybe outdated or badly installed drivers.