A simple answer would be yes, remember that electricity cannot be destroyed, only converted to motion, light or heat. In the case of your CPU, at idle it is doing less work-less heat, when under load it is doing more work- more heat. Although the power difference in terms would be minimal, to put this into context, you wouldn't recognise the difference on your power bill. The only way that you would do... was if you were F@H and running the PC 24/7. The first part of
this guide[/URL'] will give you the answer, under the heading 'Aargh, my heated core'.