Help needed, corrupted graphics all system

Hello

I need help, I have a mac pro 2008, and since some time I am experiencing corrupted graphics all over the system. The computer starts operating properly, suddenly, and looks like when I start using graphics intensice application, such as after effects, I get graphics corrupted on finder, pictures, the programs etc to a point where not even thumbnails show up properly. Restarting solves the problem however not for long.

Now I now this theoretically and the most obvious answer "is the graphic card" however I have changed the whole computer, different mac, different and new graphics card and I get the same problem. Even the RAM is different however the problem persist. The only thing that was carried from the older mac was the hard drives. The OS is the latest version of 10.10 and this problem was also with the earlier 2 versions, mountain lion and Mavericks.

Please look at the screenshots I am providing, evidently this is a software issue otherwise it would have been fixed after I changed mac.

Anybody has any idea what the problem could be?

Any help would be appreciated.