I'm going to swipe bobsag3's response and respond...

Depends on what you call "under performing."  My module would run for almost exactly 30 minutes at 70 Gh/s and then shut the machine down.  Period.  Had to power off and back on to get the Jupiter to come back up.  30 minutes later, dead again.  I isolated the problem to one particular module, even swapped it into another machine - 30 minutes later, machine dead.  Running the module by itself - 70-80 Gh/s, and machine dead after 31 minutes.  Tried every version of firmware - same result, module would run for 30 minutes about, then kill the machine it was in.  Every time.  Every version.  Every machine.

I couldn't seem to get the point across to customer service that the module would run for almost exactly 30 minutes, and then kill the machine it was running on.  I spent a week trying to explain the problem, then finally got fed up with it and "strongly requested an RMA" after playing "what happens if" games for a week and a day.  Returned the module, and it has disappeared - no acknowledgement of it arriving, no status, no return shipping info TWO WEEKS after the tracking number shows it was in their hands.