GeForce GTX 1070 Max-Q undervolten?

Since my new notebook should live as long as possible I want my GPU undervolten. Although under full load does not exceed 70 ° C but the less the better. For the GTX 1070 Max-Q is 800 mV anyway anyway the maximum, and with MSI Afterburner I find no way under 800 mV to go. Do I overlook something or do I need another tool, and if so, which is recommended?

About the Bios / motherboard but surely come under 800 mV?

By the way, just looked, that should not work under 800 mV then.