Hey all, I've got a Leadtek GTX 680 4GB (bought off eBay) in my Mac Pro 5,1 that I've been using to power 2x 23" Apple Cinema Displays (the older aluminum ones). One plugs into the DVI port of the graphics card and the other goes through a DVI->HDMI adapter into the graphics card, no issues here, works great. The only other port on the graphics card is a Displayport. After Apple's departure from the display business (oh god why), I decided to upgrade to the last displays that will work with my Mac Pro: the 27" LED Cinema Displays (Mini Displayport). I bought one and it works great with my 2013 Macbook Air through the Thunderbolt port so I know the display works. I then purchased a Mini Displayport (F) -> Displayport (M) adaptor (this one: https://www.amazon.com/StarTech-com-DP2MDPMF6IN-DisplayPort-Video-Adapter/dp/B003N3DTKY) but when I plug the display into the graphics card using it nothing happens. Rebooting does nothing, switching to the OS X display driver from the web driver does nothing. I have no idea how to fix it! I've also tried connecting the monitor as so: Graphics card HDMI (F) <- HDMI cable (M/M) <- Displayport (M) to HDMI (F) adaptor <- Displayport (F) to Displayport (F) adaptor <- Mini Displayport (F) to Displayport adaptor (M)<- Cinema display 27" Mini Displayport cable (M). This also doesn't work even though it's using the HDMI port of the graphics card which works. Any ideas?