It doesn't really matter. The SATA Express can either take one SATA Express drive, or two normal SATA drives. SATA Express is 10GB/s, but normal SATA is 6GB/s. So you don't see any benefit for a normal SATA drive even if having only one drive attache...
Like Chino said, not much of a difference. It seems to give a very little enhancement on the processing side. Very fluctuating results when you search for it on the net.When I overclocked my RAM to 3000MHz I did get a very slight improvement on the C...
