Recently I have experienced the following problem with 2x2 setup on Linux (CentOS 6 and Ubuntu):
My configuration was with 2 dual port Nvidia cards. 2x1 setup was connected to each Nvidia card, i.e. each raw is connected to a dual port nvs 295 card. So when I stack up two sets of displays, I have experienced the symptoms of the above mentioned bug.
However when I changed the configuration, i.e. connections results changed.
What I did was connected 1x2 setup to a dual port nvs 295 video card. Similarly the other set (1x2) connected to the remaining nvs 295 card. Then I didn’t experience the problem. In either setup, i.e. 2x1 and 1x2 I used the same Java JDK pkg.
Can anyone comment on this behavior? What is the best configuration (connection method) to obtain optimum results(X behavior) in Linux environment?