We covered Rockchip RK3399K processor a few months ago, as a version of RK3399 processor qualified to run at 2.0 GHz, or supporting a wider-temperature range (-20 to +85°C) at 1.8 GHz.
We found out about the new processor, as Kobol was working on a Helios64 SBC designed for NAS that featured RK3399K SoC. At the time, we just had a drawing of the board and some specifications, but now the company has announced pre-orders for the board and a complete 5-bay NAS kit will start next week and the actual shipping start in March.