This is another great job at firmware mods!!
I had raised my stock firmware up to 397mhz and was getting about 511mhs but I am sure at more than 800w advertised. I think I remember initially testing and it was running at 820w stock.
Anyway, now I have it tuned at about 406 freq 5 power level on most of the chains and getting 520mhs and only pulling 755w. Also running the fan lower and its not making a lot of noice, albeit nothing like a d3 before your firmware.
Thanks!!