The problem with the video card Radeon RX550, with the installation of the kernel version kernel-4.18.10-300 and kernel-4.18.12-300, the memory and core frequency has stopped decreasing, all the time the video card runs at GNU frequencies - 1183/7000 (memory) MHz. Version 4.18.9-300 the frequency is reduced by the processor and the memory of the video card.