This is not the first time that a Seasonic product manages to amaze me and it surely won't be the last! The new fanless Platinum 520 W unit is a great performer with ultra-stable rails that deliver very clean outputs. It is highly efficient under severe conditions, utilizes a fully modular cabling system, and its protection features, especially OTP (Over Temperature Protection), work well, which will save the unit from damage if you surpass its limits. Seasonic also made sure to include an extra-long warranty, which is pretty special because the SS-520FL is a fanless unit that will, compared to normal PSUs, operate at increased internal temperatures. The only downside of this unit is that it only comes with two PCIe connectors, which is a weird choice since it could easily handle two additional connectors to support up to two VGAs with double PCIe sockets each. But its modular design does allow for such a problem to be remedied easily with the use of cables that feature two PCIe connectors. Seasonic should look into this matter soon, and they will hopefully realize that having no more than two PCIe connectors greatly restricts this fine PSU's usability.
Your choices are pretty limited if you are looking for a fanless PSU, especially if you seek a Platinum efficiency one. The Seasonic SS-520FL's platform easily allows this unit to confront and eclipse its competition by providing top performance for a price that beats every other fanless Platinum PSU out there, which makes its purchase a no-brainer.