No such thing. "Quiet" fans just move less air, for situations when you don't need that much cooling. That does not apply to a 1 KW miner in a relatively small box. You can reduce the sound a little or change the frequency of the sound with different fans, but probably not worth the cost.

You could try opening the box and running it with a large room fan blowing on it instead of the case fans. Some chance that will work, but YMMV. I was able to do that with a bunch of ASICMiner blades back in the day. It was still somewhat loud.

BTW, what's the deal with the bitmain web site being down? Back up now.