My zotac 3080 goes to 718mV, but i'm not sure if this is the case for all 3080 - my other rtx cards have different minimum voltages.
FWIW i use awesomeminer to set the voltage. If it goes too low, the memory will drop to 5000mhz.
What hash are you getting now with your AMP HOLO?
Can you share you OC settings?
Fan speeds:
Memory overclock:
Power:
Temp:
Hashrate:
Thanks!