the optiplex 390 list that the highest cpu that it cam out with is an I5 2400. I have one with an I3 in it but I see I can buy an I5 2400s for very little. will the "S" model work with it? I looked at benchmarks with the 2400 vs the 2400s and know the non s one is slightly faster, but I just want to be sure , Is the S model accepted in all boards that take the ones without the s?