I was reading somewhere else (or it might have been on this thread) that PCIe x8 adapters for x16 cards are fairly expensive (340.00 EUR or at the time of posting, about 413.00 USD).
That's what I remember reading.
While you're probably right that the PCIe x1 doesn't offer much in the way of bandwidth; it's cheaper than going with an adapter and also the video card of choice.
I know that for my Solaris systems, they have ported the drivers from Linux using the XFree86 porting kit and it works fine. (I don't game with it, so I won't know what that's like.)
May I ask why it is that you choose that board as the platform for building your system?
If you intended to game; I would have thought that you would have looked in/thought about your options (or in this case, lack of options) for video cards.
It might be possible for you to use that card, and game in Linux using Cedega.
While you are probably right that ATi graphics cards aren't as good as nVidia (I don't know, because most of the stuff that I deal/work with is 3DLabs), I would think that the only reason why it is the specific combination of programming and gaming is that you're writing games.
In which case; if you're doing the graphics development; I would have figured that you would use a professional graphics solution (like 3DLabs) for the development work; compiled, and then running the game itself on another system that is design with that purpose in mind.
Else; you're either stuck with the limitations in terms of meeting performance criteria with the system that you have, where compromises have to be made on the development front and on the gaming front, or that attempts to try and satisfy both requirements becomes a lot more expensive than it has to be.
I am also presuming that GPGPU is referring to general purpose graphics processing unit. If that's the case, isn't that a PCIe x1 has more bandwidth than an AGP4X and also possibly AGP8X?