Less VDDC when overclocking 7970

[grandpatzer]

So I'm using Kombustor to test out clocks.

Without touching volts when I run 1125/1375 gpu-z reports VDDC 1.051 (starts 1.057 then goes to 1.051)

Without touching volts when I run 925/1375 gpu-z reports VDDC 1.057.

This is 21% core overclock.
This give 19% more fps in Kombustor.

Question:

A bit weird that more speed needs less VDDC?

Edit--> I also now overclock memory so: 1125/1431 and not even 1fps increase, also the gpu-z shows 2900mhz memory clock

 

[xSystemFailurex]

So I'm using Kombustor to test out clocks.

Without touching volts when I run 1125/1375 gpu-z reports VDDC 1.051 (starts 1.057 then goes to 1.051)

Without touching volts when I run 925/1375 gpu-z reports VDDC 1.057.

This is 21% core overclock.
This give 19% more fps in Kombustor.

Question:

A bit weird that more speed needs less VDDC?

Edit--> I also now overclock memory so: 1125/1431 and not even 1fps increase, also the gpu-z shows 2900mhz memory clock

I don't think it's so much NEEDING less as it is USING more.

Your V is drooping.

Edit:--> Mem OC would theoretically give better frames with more image quality. You see no diff because bandwidth is ample enough for your benchmark regardless of mem clock.

(Correct me if I'm wrong, [H]-ers.)