The stiffness matrix of $Ax=B$ system of linear equations, where $A$ is an $n\times n$ symmetric matrix stored in the form of symmetric skyline matrix, that is associated with a finite element model of 3-D elastic solids, when reordered with the reverse Cuthill–McKee algorithm doesn't result in a skyline matrix with limited RAM storage space requirements as would happen with a 2-D problem.
What is the best algorithm for the 3-D case?