As Tom said the readings from 3DMark are inaccurate, particularly of the memory frequency.
Even with more accurate tools such as CPU-Z and Task Manager (on Windows 8) you will need to double the value to get your actual figure (so if shown as 800MHz x2 = 1600MHz).
A little OT I know but Task Manager on my Windows 8 Pro system shows my RAM speed correctly at 1600MHz.![]()