You can freely download and use a beta-version of Rendergin from the German Numenus. It is a standalone rendering application with primary attention to render complex and large models using your GPU, even with "low end" GPUs (be sure to read the requirements to understand what they mean by that). They specifically target NURBS models without triangulation, but support other geometry as well. The list of supported applications includes 3ds Max, SketchUp, Blender and Cinema4D (and several others).
Go to http://www.numenus.de/rendergin.html to download the installer. Windows and OSX are supported and a Linux version can be requested. During the beta, you can use it in trial mode and request an unlock code, which will be freely provided until the software is officially released.