I posted this same post in german forum, what do you guys think on the english side?

I have a bunch of old S9's laying around, some work, some are in pieces with broken parts, etc.  I'm working on making some custom miners.  I have a bitaxe on the way (backordered, ordered it like 3-4 weeks ago), I like how that is 400G+ for only 20ish watts.  I'm testing out the efficiency I can get with 1, 2, and 3 hashboards and varying amounts of power to each one (i'm using braiin os).  Do you guys think I should just try to make one that uses the least amount of power but isn't the most efficient, or uses a little bit more power and work on getting the most th's/watt?