First of all it looks really strange to me that your processor is running at 3.0 Ghz with 1.000 voltage. Does k10stat tell the same power state table as tpc does? I'm worried about some voltage conversion errors (even if I double checked them).
BTW, you should let the processor do a pstate transition to really apply new settings. I explain: when you use tpc and change the core voltage, the processor has to reenter in that pstate to apply new settings. When the pstate changed is the slowest pstate (the pstate used when the processor goes idling) you need to put a load to let the processor go out of the pstate and then reenter.
Unfortunately I had no chance to test the behaviour on a AM2 motherboard with a AM2+ processor, so I can't be more detailed on this.