The problem with Radeon based graphics card are to my knowlege not supported for use with Iray.
If you want to use DAZ studio with Iray rendering an Nvidia card is highly recommended.
Other (paid)render engines might work with a radeon based card,
recommend you find out before you buy
I use Iray because it comes free with DAZ3D.. other renderengine might not be free.
DAZ Studio and Linux are not quite compatible IIRC even with WINE.
Good luck finding out what you want to use and what will work and what not
Ok. I wonder, how well are "general gpu computing" facilities supported on AMD-based cards?