You need to make sure the PP_OVERDRIVE_MASK flag (bit 14) is set. E.g., amdgpu.ppfeaturemask=0xfffd7fff See the documentation in the driver for more: https://cgit.freedesktop.org/~agd5f/linux/tree/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c?h=amd-staging-drm-next#n469 Also, If the vbios on the particular board does not support overclocking, the functionality is not exposed on 4.17 IIRC.