NVIDIA Quadro 4000 2GB GDDR5 Video Card - DISCOUNT ELECTRONICS
Refurbished: nVidia Quadro 4000 2GB GDDR5 PCI-E x16 2.0 Graphics Video Card With DVI and DisplayPort Outputs 38XNM Standard Height Workstation Video Card - Newegg.com
NVidia Quadro 4000 Q4000 2GB DDR5 Video Graphics Card DVI DP for Mac Pro 3.1-5.1 | eBay
NVIDIA Quadro RTX 4000
Amazon.com: NVIDIA Quadro 4000 by PNY 2GB GDDR5 PCI Express Gen 2 x16 DVI-I DL, Dual DisplayPort and Stereo OpenGL, DirectX, CUDA, and OpenCL Professional Graphics Board, VCQ4000-PB : Electronics
Ars Reviews the Quadro 4000 Mac Edition: NVIDIA's sole Mac offering a promising start | Ars Technica