Comment 47 for bug 1049630

It's disappointing, but I think there are just too many bugs and not
enough coders to fix them, and they've got to prioritize. -- on top of
that, there's not a *really* good method out there of evaluating the
impact of a problem. This is obviously a high-impact problem,
considering how common the card is, but it's slipped between the cracks.

As to your idea -- I think that radeonhd drivers are incompatible with
the newer versions of X -- which is why they were phased out anyways.
Unfortunately, the newer drivers obviously don't work right for a lot of
people.

The best bet to getting a fix is probably emailing the maintainers of
the new driver -- getting on mailing lists and discussing it. I long
ago gave up on fighting this particular fight.

If it helps, this is definitely a sideport ram issue, and disabling
sideport ram in the BIOS fixes the problem -- however, many BIOSes do
not allow you to do this.