Created attachment 138864 [details]
full dmesg

Arch Linux 64bit with kernel 4.16.2 and linux-firmware 20180402.8c1e439 with a
Sapphire RX480

[    2.081160] [drm:gfx_v8_0_ring_test_ib [amdgpu]] *ERROR* amdgpu: IB test
timed out.
[    2.081205] [drm:amdgpu_ib_ring_tests [amdgpu]] *ERROR* amdgpu: failed
testing IB on ring 9 (-110).
[    2.227850] [drm:amdgpu_device_init [amdgpu]] *ERROR* ib ring test failed
(-110).

I haven't noticed any problems yet other then the error message when booting.