Which is the lowest frequency for 7700hq when idle?

Just a simple question, there's no issue about performance and temps here, but I'm going for the maximum efficiecy and battery life this device can get. Already undervolted cpu, igpu and gpu, changed power config and stuff. Only one thing left.

My helios 300, g3-572 is equipped with a 7700hq, and the lowest frequency I ever saw it running is around 1600 MHz. In the webz I saw many screenshots of ppl having their cpus at 800 MHz. As far as I have noticed, there's no background app running, cpu package even reaches c8 state, and I already setted minimum processor usage to 0% in advanced power settings.