Good product, but not quiet and useless in most cases
I bought this power supply together with two others of the same brand, a GX-650 and a GX-850.
This power supply, although fanless, is not silent. It emits several low volume sizzles, "coil whine", like many other power supplies, including high-end ones. Since there is no fan, these sizzles are more audible.
Where I think this product is relatively useless by design is that the sizzle makes as much, if not more, noise than the fan on my GX650 and 850 when used at low load. It's worth mentioning Seasonic's remarkable work on the noise level of these cooling systems. They are impressively quiet.
Therefore, you might as well buy a 1000W GX product, and only use it at less than 700W. The volume will be the same as for a 700W fanless, and it will be cheaper.
Beware in particular to those who would like to build an exotic configuration totally fanless. I'm thinking for example of configurations placed on a desk, or even open. You have to expect a very slight noise from this power supply.