There is no definitive answer, as the effect of putting a PC tower on carpet will depend on a number of factors, including the thickness and type of carpet, how heavily the tower is weighted, and how rough the surface is. Generally speaking, however, it's unlikely that placing your PC tower on carpet will cause any major damage. If you do notice any problems with your tower after moving it to carpeting, such as wobbling or instability, then it may be time to consider replacing your flooring.