Comment # 6 on bug 104412 from S.H.

Hello,
Last night I was able to get my hands on a Gigabyte RX460 and did some testing.
Booting and normal startup with the Gigabyte also only used 4k@30Hz but I was
able to reach 4k@60Hz by adding a modeline via xrandr.
With the Saphhire I am not able to get 4k@60Hz even with a custom modeline set
via xrandr.
Something seems broken here and I don't think both vendors messed up their
cards.