Created attachment 699700 [details]
dmesg of working kernel 4.7.6-1-default on Athlon64 inside Virtualbox
I tried booting kernel-vanilla-4.8.4 from the Tumbleweed repo, with the same
problem.
I also tried booting *without* an initrd (by removing the initrd line from the
boot menu entry), and it behaved the same.
So I suppose we can rule out a problem with the initrd.
A dmesg from me too is attached, kernel 4.7.6-1-default inside VirtualBox with
an Athlon64 3000+ on the host side.