Used Nvidia Quadro 6000 6GB 384Bit Q6000 Professional Graphics Card - AliExpress
Amazon.com: HP 616078-001 NVIDIA Quadro 6000 PCIe graphics card - With 6.0GB GDDR5 GPU memory, max resolution 2560x1600, max power consumption 204Watt, one Dual Link DVI-I and two DisplayPorts connections : Electronics
nVidia Quadro 6000 6GB GDDR5 PCI-E x16 2.0 Video Card DVI DP [Quadro 6000] - $725.00 : Professional Multi Monitor Workstations, Graphics Card Experts
NVIDIA Quadro 6000 6GB GDDR5 DVI 2 DisplayPort PCI-Express Video Card (part_B00LG6YPEE) - Newegg.com