@Dietmar
From what I've found on Gigabytes website.
https://www.gigabyte.com/WebPage/917/amd600-bios.html
On the Favorites (F11) page.
AMD at least still has CSM.
(It might only apply to 600 series and not 800 series chipsets though)
edit:
https://www.gigabyte.com/WebPage/1081/amd800-bios.html
All good, CSM support still there on the Main Menu page.