It is debatable as to weather there is a good reason why the gamer cards won’t play well with SolidWorks or not. Gaming cards and CAD cards are optimized for different purposes. Gaming cards are set up for a single window, enormous amounts of texture information and can trade accuracy for speed. CAD cards are set up for multiple windows and put a premium on accuracy. More of the difference is in the drivers than in the hardware. In the end, gaming cards typically work for CAD, but with some quirks, which you may or may not be able to live with.
In my opinion, the true downside of using the unsupported cards is that they are just that, unsupported. When you have problems with crashes or most anything else, one of the first things your VAR, or the people on this forum will ask is “What card are you using and which version of the driver?” If you answer is not a certified combination, you will generally be told that it is likely a problem with the display drivers, and to switch to a certified solution.
You do not have to place much value on your time before it makes sense to bight the bullet and use a certified card, even though it costs more or the performance specs are less.
Eric