I have also noticed that Vcore has to be higher if running higher memory speeds well on my chips that is true. Not just higher VCCSA and VTT but higher Vcore too. From DDR 2133 to DDR 2400 I need 0.015v extra and another 0.005+ extra for DDR 2500+ to achieve stability and maintain tight timings this is at 5.0 - 5.125ghz. With the IMC being on the chip this makes sense. SO many variables are effecting Vcore needed with sandy- E. I would not worry so long as your system is stable and does what you need while maintaining resonable temps your fine.