I need to lower them off if my software finds hashboard or fan issues. A powered off machine is easier to find on a rack too. My sense is that Bitmain hasnt implemented it yet in BMMiner.
if your miner has a fan / board issue, it will not be mining, it will be almost "off" , only the fans and the control board will be running , but you can still spot the faulty miner by turning the lights off and looking for a red blinking led instead of green because that's what the miner does when there is something wrong.
anyhow, i guess if you have a large number of machines, or even a mid-range scale, you should label them ! it's important to do so, if you have 1 faulty miner you can spot it, but what if 2 or 5 ? how are you going to know which one is which? it will be time consuming IMO.