For my system (reported Bug 54988) it starts up now and works for a RAM size of
3G.

But after logging into the gnome desktop the screen becomes blurry and 
and while trying to open any gnome menu, the screen gets scrambled now.
This is even a problem when i boot with mem=2G - this used to work with the
current version of the fedora driver in kernel 3.5.4.

Seems the DMA problem is gone, however some new bugs are showing up :-)

System Description is still the same as 54988. I am running a current fedora
kernel,patched with nouveau from 2nd October.

Linux version 3.5.4-2.localnouveau.fc17.x86_64 (root@baldur) (gcc version 4.7.2
20120921 (Red Hat 4.7.2-2) (GCC) ) #1 SMP Wed Oct 3 11:36:49 CEST 2012