Voltage droop? Is this acceptable?

I've been experimenting with Gigabyte's automatic overclocking tool today, and I noticed that my voltages droop under load.

I have them set to 1.6v in the BIOS, but normally CPU-Z reports them as 1.584. Under full load, it sank to 1.552v. Is this normal/acceptable? Or is this an issue?

That is normal, and remember, the onboard sensors are not very accurate, so don't worry.