My partner has recently got hold of an old Mac Pro 3.1 A1186 EMC 2180 and has asked me to get it sorted for her. She wants to use it for work and she is in the commercial video and audio industry so needs to be able to rig it up to 4K projectors for video mapping and other display purposes. It currently houses an ATI Radeon 5770 card which has one DVI port and two mini display ports. As far as I can tell this card won't output 4K resolution. So my question to all you knowledgeable types here, what card can I use to accomplish this?