Professional 2D: NVIDIA® NVS™ 300, NVIDIA® NVS™ 310, NVIDIA® NVS™ 315, NVIDIA® NVS™ 510
Entry 3D: NVIDIA® Quadro® 410, NVIDIA® Quadro® K600, AMD FirePro™ V3900
Mid-range 3D: NVIDIA® Quadro® K2000
High-end 3D: NVIDIA® Quadro® K4000,†† NVIDIA® Quadro® K5000,†† NVIDIA® Quadro® K6000 (AMO only),†† AMD FireProTM W7000,†† NVIDIA® Tesla™ K20c,††
NVIDIA® Tesla™ K40††
http://h20195.www2.hp.com/v2/GetPDF.aspx/4AA4-0128ENUC.pdf
The workstation is a 2013 model. HP has been known to limit video cards to certain ones. I would try to find out if someone else has successfully used a newer model before buying one. Power requirements are another factor too.