So I recently purchased some X3 Units, and 2/4 boxes burnt down. One was burnt to complete rubbish (picture below), worst part was the blade was burnt from one end to the other so the machine stayed on causing quiet the smoke and an awful smell of burnt plastic, spoiled eggs, and burnt electronics. LUCKILY I was home..I was able to unplug em and throw the unit outside in my shed.
As for my second unit, it kept going on and off and hashing extremely low. The smell of burnt plastic kept coming and going. Opened it up and saw it begging to blacken/char on the metal of the blade; needless to say I threw it outside as well as the major fire hazard wasn't worth the cost of my home and my other mining gear or better yet my life.
Neither of the units were at default frequency; in fact all my units were under clocked and on its own dedicated 20 amp breaker.
So yeah..not sure I'll be using Black Arrow products anymore.