Actually, you can safely install the Sid fglrx packages in Jessie and Wheezy, and they are patched to build with the 3.14 at least through the 3.16 kernel. They were also easy to backport on a Wheezy base to go along with a backported 3.16 Liquorix kernel. I don't know what's keeping them out of Jessie.yzT wrote:your problem is an incompatibility between ATI cards and the latest kernel.
I didn't test in depth, but the current kernel 3.16 and its radeon driver are not working properly. If you want to install fglrx, you need to downgrade to kernel 3.13 as it's the latest supported by the beta version (14.6)
The driver source straight from AMD will have those problems, though.