I have a same issue, but my full speed is acceped by the pool. Anyway I installed blizz's moded frimware and at least it is less noise. After frimware upgrade chain 0 still not visible.
That's really odd... I've contacted Bitmain so let's see what they have to say.
What settings do you have on the blizz firmware? I'm contemplating using that but because I live in Singapore, the temperature here is around 30 degrees Celsius almost all year round and I'm afraid lowering the fan speed will cause overheating.