If I install efudd's firmware how do I set different frequencies for each board I do I have to set them in the antminer web interface
You can set frenq values under extra config arguments (miner config) while configuring a flight sheet. For example:
"bitmain-freq": "725"
"bitmain-freq1": "725"
"bitmain-freq2": "725"
"bitmain-freq3": "725"