I've just had both labels come off my cubes so I took off the fan and removed the labels.  One of the fans was dragging on the label and I had to shut it down.  Prior to the shutdowns, both cubes were running well on high clock.

 Now I can't either cube to use more than 3 boards properly.  I've taken each apart and reseated all the boards, took apart and shuffled the boards and cycled the power, cycled the clocks, reset them and I'm about to pull my hair out.

I've never seen anything so finicky/touchy as these bloody cubes. 

My advice is if yours are running reasonably well just leave them alone.