They aren’t strictly relative. I can have a GPU load of 30% but still a Power Consumption of less than 10% (again, with a base idle of ~6%, so barely more). And also with core and memory at idle speed or very near idle speed.
I’m not sure if that means 30% load of idle core speed or 30% of max core speed, but I suspect the first. Would make more sense. The point is: what kind of demand is placed on the GPU makes all the difference as to what the power consumption really is. It can be a light load or a heavy one at the same core speed I think. With vastly different power demands. These modern GPU’s are really clever in their scaling ;D
Edit: I’ve just installed GPU-Z 1.1.9.0 and it shows the exact same readouts.