A good GPU for a CAD workstation needs good 3D performance, multiple displays at high resolutions, and a flexible form-factor. Looks like the FirePro W4300 delivers the goods.
AMD FirePro graphics cards typically deliver great price / performance from entry-level 3D to ultra-high-end graphics. And for a short time, AMD is giving great deals, too. Check it out.
AMD FirPro GPUs deliver remote, shared professional GPU performance with hardware-based virtualization.