Linux amdgpu error on startup

[hcwh]

Using the following setup:
MSI Z170A Gaming M5 motherboard
ASUS Strix ROG RX 580 OC 8GB GPUs (original BIOS)
Xubuntu Linux 16.04.2 (kernel 4.8.0-54-generic)
amdgpu-pro-17.10-414273.tar.xz drivers
Claymore 9.5 mining software

If I install any of these GPUs on the first PCIe slot (1x) and everything works fine.

If I try to add any more GPUs, I get the following errors on startup and the machine fails to boot up:
3.213641 [drm:gfx_v8_0_ring_test_ring [amdgpu]] *ERROR* amdgpu: ring 2 test failed (scratch(0xC040)=0xCAFEDEAD)
...followed by similar lines for ring 3, ring 4, ..., ring 9 and then...
4.999827 [drm:sdmav3_0_ring_test_ring [amdgpu]] *ERROR* amdgpu: ring 2 test failed (0xCAFEDEAD)
5.000121 [drm:amdgpu_device_init [amdgpu]] *ERROR* hw_init of IP block <sdma_v3_0> failed -22
5.000381 amdgpu 0000:04:00.0: amdgpu_init failed

I've installed multiple cards on this motherboard of other brands (PowerColor, Sapphire, Gigabyte, XFX, etc.), but this one is causing trouble for some odd reason.

Has anyone ever seen this error and know what might fix it?

[zz03]

Hey exactly my issue. It more looks like it is related to specific PCIe slots though, not necessarily specific GPU cards.

How did you fix it?

[punkoivan]

try to update you kernel, on Ubuntu it's called HWE.