As a forewarning to casual Linux users that might be running Nouveau for your GeForce hardware and once in a while update against the Oibaf PPA or Ubuntu Mainline Kernel PPA, it appears there's some bad issues right now affecting at least Ubuntu Unity users... Today in trying out several graphics cards from Kepler GPUs to old GeForce 9 hardware, there's very evident on-screen corruption and rendering problems with all the NVIDIA hardware tested thus far.
While the Ubuntu 14.04 LTS system with the Oibaf PPA and Ubuntu Mainline Kernel daily build is playing nicely for AMD Radeon and Intel HD Graphics, I haven't yet got a NVIDIA graphics card playing well on Nouveau with this latest combination.
At least with this problem seeming to affect many different GPUs from NV50 through NVC0, hopefully this issue will get addressed correctly.
Once the Nouveau driver is back to playing well with my assortment of NVIDIA GPUs, I'll continue on with the multi-vendor tests though in the next day or two will then be the AMD Radeon results for this latest Steam/Source Engine Linux benchmarking on the open-source drivers.
Of course, for most gamers the Nouveau driver will be off-limits anyways until re-clocking is figured out, the performance will likely suffer.