Quad-Monitor AMD/NVIDIA Linux Gaming: What You Need To Know
After the NVIDIA binary driver testing was finished (benchmarks shared later in this article), I went to see how the Nouveau driver would handle the four displays on the Linux 3.12 kernel and with a Git snapshot of their xf86-video-nouveau X.Org driver. The Nouveau quad-monitor tests happened from the GeForce GTX 680, GTX 760, and GTX 770. The higher-end models couldn't be tested since the Nouveau support is in poor shape for these new GPUs.
When the system booted up, three of the displays were black while the fourth display was a solid green. When SSH'ing in and checking out the dmesg and Xorg.0.log outputs, there wasn't any useful information provided. After some reboots and other quick tests, the concept of testing out the open-source NVIDIA driver in a quad-monitor configuration was abandoned. Besides, until there's proper GPU re-clocking support the performance would be way too slow for anything useful -- it's already unbearably slow in some tests at 1080p due to the hardware not being able to run in their highest performance states.
Next up for testing was the AMD Radeon R9 290 with the Catalyst 13.11 Linux driver. With the R9 290 and the four 1080p displays, everything booted up. The displays can be easily configured using the AMD Catalyst Control Center Linux Edition, or like the NVIDIA binary driver, AMD Catalyst also supports RandR. Configuring the displays using AMDCCCLE is very easy to do in a graphical manner. There isn't quite the number of options found as in NVIDIA-Settings, but still it's enough for all key settings.
After running the R9 290 quad-monitor benchmarks on Ubuntu Linux, then I changed out for some other graphics cards like the Radeon R9 270X. When booting this graphics card and some of the other high-end graphics cards, that's where problems began with the Catalyst driver. When booting the R9 270X, only three of the monitors lit up and there was an error message of "Could not switch the monitor configuration. Could not set the configuration for CRTC 150."
When getting into the AMD Catalyst Control Center for configuring the four displays -- which again were two DVI heads, a HDMI head, and a DisplayPort head -- the fourth monitor remained disabled and could not be enabled. From the swapping of graphics cards and display connections I did, the Catalyst Linux driver is just refusing to enable mode-setting for four displays on the 2GB graphics cards. With the R9 290 3GB edition there were no problems. The 2GB NVIDIA graphics cards had no troubles with mode-setting or limited performance due to vRAM pressure, but the Catalyst Linux driver refused to operate on the quad-monitor setup. Unfortunately, with AMD not sending out hardware recently, I don't have many recent Radeon GPUs and those that I do were GPUs I purchased -- including the Radeon R9 290 -- so this testing is limited on the AMD side.
When running the performance tests on the Radeon R9 290, one Catalyst Linux driver issue encountered was the quad-monitor setup not working for Unigine Heaven 4.0 and Unigine Valley 1.0. The tech demos were set to run full-screen at 3840 x 2160, but for these two tests they would end up running at 1920 x 1080 on just the primary display. This issue didn't happen for the same tests/settings with the NVIDIA driver. The older Unigine tech demos and other Linux games ran fine with Catalyst.