Before revision:  We find that high single-core performance and a correct choice of the number of cores used on the chip are the essential factors for lowest energy to solution with minimal loss of performance . In the highly parallel case, these guidelines are found to be even more important for fixing the optimal performance-energy operating point , especially when taking the system's baseline power consumption and the MPI communication characteristics into account.
After revision:  We find that high single-core performance and a correct choice of the number of cores used on the chip are the essential factors for lowest energy to solution at minimal performance degradation. Then we extrapolate to the MPI-parallel level and quantify the energy-saving potential of various optimizations and execution modes, where we find these guidelines to be even more important for fixing the optimal performance-energy operating point , especially when taking the system's baseline power consumption and the MPI communication characteristics into account.