WOW!...EXCELLENT chart...you are hired!
just a screenshot of something knocked up in a couple of minutes in Excel

Yep so the HD score is a direct function of faster memory performance say 5% , yep can buy that

So if we eliminate the DDR3 impact :-
is 404+636 , are we saying gain is all down to memory, it'a a pity the total isn't additive. It's not an average either (Sum element score & / by 4) . We could do with someone with a X48 DQ6 to repeat your tests

Anyway Gigabyte rules OK