S.C. Code Ann. § 29-3-630

No sale under or by virtue of any mortgage or other instrument in writing intended as security for a debt, conferring a power upon the mortgagee or creditor to sell the mortgaged or pledged property while such power remains of force or has not been revoked by the death of the person executing such mortgage or instrument, shall be valid to pass the title of the land mortgaged unless the debt for which the security is given shall be first established by the judgment of some court of competent jurisdiction or unless the amount of the debt be consented to in writing by the debtor subsequently to the maturity of the debt, such consent in writing to be recorded in the office of the register of deeds or clerk of the court where the mortgage or other instrument in writing given to secure such debt is or ought to be recorded. But if the mortgagor be dead it shall not be necessary in any foreclosure proceeding first to establish the debt by the judgment of some court of competent jurisdiction in order to obtain a decree of foreclosure and sale.