I've used a g550 for about 10 years, running in dual-head mode.
This card is ok, but, since my monitors grow, the card was to slow.
So, because I like the matrox hardware, I got a P650 from a friend (before reading here
the card is ok, but the drivers are not. I am also not a gamer, but a few apps need opengl,
and that is a horror with the matrox drivers. At last, it runs here in 16 bit depth, but
the opengl implementation is too old. so most apps wont compile.
Now, I bought an old FX 5200
), run the nvidia installation, and it works.
The quality is ok for me, I cant see any difference.
Sad to say, but I think, for linux matrox is not a good choice anymore.