First of all, thank you Blissz for the work. My first message here at bitcointalk, cheers!!!

Is that normal having a hashrate of one board disappearing and coming back all the time?

The power usage still same when it happens but as I am mining in nicehash and when I see there is a decrease in hash rate also on their dashboard, what can it be? I am running my D3 at about 9500Gh/s(only two chains) as I am using a pc PSU while they ship APW3++.