BTW, what benchmark are you using to do your testing, and what settings are you running? Generally speaking as resolution and AA levels go up, memory OC scaling % tends to go up (although it's unlikely to exceed the core scaling %).
For example, if you compare Vantage Performance results vs. Vantage Extreme results, you'll find that the core OC scaling will go down a bit, and the memory OC scaling will go up a bit.
Edit: Oh, I see, 3dMark11 on stock settings. This test is probably going to heavily favor the core OC. Low res, low AA, and some tests have tessellation (which is totally core speed dependent), so ... yeah ... memory OC isn't likely to do a whole lot in that scenario.
You should also try it w/Crysis maxed out running 16xQAA, or Metro maxed out (leave off advanced PhysX though).
Edited by brettjv - 3/29/11 at 2:12pm