Minerbabe : amgpu error at boot sequence and about OC of VEGA 56

Hi and thanks for this OS its quite amazing simple. I have 2 questions (details on my config will follow) :

1/ At boot load i get “amdgpu 0000:03:00.0: Invalid ROM content”. I am wondering if it is a problem and how to correct it (and if its linked to my second question) ?

2/ When i try to OC (in order to diminish the power consumption), it seems to work (minerbabe reports that the OC is what i asked, for example 1100 and 850mV for the GPU), but, it has absolutly no effect on power consumption (it still maxes at 300W per cards). Am i doing Something wrong ? i d appreciate any imput.

I am using an H110 BTC pro, so far 4 VEGA56, mining C31, cpu load and mem load seems to remain Under 20% for 4 cards (i intend to upgrade to 8, everything is ready, but i need first to lower consumption of 4 cards Under 1100W total)

Many thanks to the community