South Carolina presently has a statute that provides if your will was properly executed in another state, it will be considered valid in the state of South Carolina.
However, it is usually desirable for a resident to execute a new will in South Carolina for several reasons. Since your out-of-state will was drawn with the laws of the other state in mind, it may well be that your will now needs to be changed in light of South Carolina law. Additionally, if you should die while a resident of South Carolina, your will would have to be probated in the South Carolina courts. The "providing of a will" requires that a witness to the will swear that he saw the decedent sign the will. Since your out-of-state will would have out-of-state witnesses, the extra time and cost of providing your out-of-state will could be considerable.