Originally Posted by CLC
Unfortunately it doesn't seem to fix the issue on the Sabertooth 990FX, either.
I use Sabertooth 990FX (BIOS 1102), AMD FX 6100, GeForce GTX 550 Ti, GeForce 9800GT with 16GB RAM on Fedora 16 64bit (3.3.0-8 kernel) with the NVIDIA kernel module version 295.33. When IOMMU is activated in the BIOS - regardless of IOMMU reserved memory settings or memory remapping settings - I get the same errors in dmesg as Deanjo on page 1 and no X. When I use the nouveau module, I don't get these problems but 3D acceleration is painfully slow and makes the PC unsuitable for running as a Xen virtualized multi-OS, multi-user system (which is what I built it for). So that project's been on hiatus waiting for a patch or fix.
It completely fixed the issue here. I setup another two Sabretooth systems here and they work fine with IOMMU (cards in use with the three systems GTX-580, GT520 and GTX-275). The M5A system is running fine as well with IOMMU and a 8800GT. All are running openSUSE Tumbleweed 64-bit. It is quite possible however that the choice of processor also plays a factor here. All the systems that have working IOMMU here are using Thuban processors so maybe the fix did not apply to BD processors.