I just received an antminer A3. I set it up, and it worked fine for the first 8 hours. However, I noticed that it lost one third of its hashing capacity. Upon further inspection, X's would appear under Asic status for a random hashing board, it would change from one reset to the next. After multiple restarts, focused completely on the second hashing board. I have tried using different pens from the power supply, but nothing works. In my lack of understanding how Asic machines work, I fiddled around with settings to see if anything would revive the second hashing board. Unbenounced to me, I might have overclocked the antminer in my attempt to revive the hashing bored, as I increased the frequency from the default. Does this mean I have voided the warranty? That would be my luck. If you can help in any way, please let me know. I would not be able to reach a return on my investment with only to hashing boards.
I would first question the power supply you are using, are you using a single PSU? If yes, what wattage is it rated for? If it's less than 1500W, you need to use a better/larger PSU.
Also, I would recommend you underclock the A3 as many have had issues running at stock speeds. I have one arriving this week or next and my first step will be to lower the clock speed of it.