I use RX580 Nitro+, and get 24 MHs only.
On the boot screen I see:

GPU[0]       : Supported GPU Memory clock frequencies on GPU0
GPU[0]       : 0: 300Mhz *
GPU[0]       : 1: 1000Mhz
GPU[0]       : 2: 1750Mhz
GPU[0]       :

Where is 2000Mhz and more?