Certified hardware list for Autodesk AutoCAD (with
FAQ)
Certified hardware list for Autodesk Inventor
Certified hardware list for PTC Pro/ENGINEER (applies to Wildfire 4.0; for others, see
here)
The real story is the drivers—the hardware on most CAD-certified cards is very similar to the hardware on a consumer-grade card. Just about any mid-to-high-end consumer-grade graphics card will work for the average FIRST team's CAD work.
Even among consumer-grade drivers, you may have to try a couple different revisions to find one that co-operates with your chosen CAD program. If you're experiencing graphics slowness, or visual problems, try another driver version (newer or older).
Here's something else to consider, if you're interested in anecdotes, and not tied to a particular CAD package—I've found (several revisions of) Pro/ENGINEER quite usable on systems with extremely modest capabilities, but have had much less success running Inventor (or even recent versions of AutoCAD) on similarly-equipped machines.