So you set it to 9.4v for every frequency. There really is no underclocking then since when you set the voltage it sets that for each of the 21 lanes. 9.4/21=0.44761V a chip. If you are trying to underclock it for better efficiency you would need to recompile bminer and lower the voltage to whatever works best for whatever frequency your using. This is only good if you are trying to get the fastest th/s and don't care about losing efficiency since autotune was made for increased efficiency.