Using Black Magic Card with Mac Desktop and FCP

I am building a pepped up edit system using a modified 2009 Mac desktop. Mac Book Pro not going to handle 4K. When using FCPX do I need to purchase a Black Magic AV output card to get the monitor out function to work with my edit program? Can't seem to find the answer on-line. There is a HDMI out on the Radeon graphics card - but I don't think it works that way. Thanks for your advice!

For color accurate work and 4K you will need the Intensity Pro 4K card from Blackmagic. It will work with most software packages Final Cut included. Myself I use a Thunderbolt MiniMonitor for FullHD monitoring on an 27" CG Eizo. Heres the link to the Intensity Pro 4K card:

https://www.blackmagicdesign.com/products/intensitypro4k

If you work on class 1 broad cast monitor then you will need one of the more expensive DeckLink cards from BMD with SDI connectors.

Thanks Daniel for your helpful reply. I am taking it slow and easy - first image out. Will the Radeon accelerator graphics card board give an HDMI any image out if I adjust the preferences on AV out in FCPX ? I don't think so. I probably need to buy the Intensity card, right?

Apple reserved this 4K monitoring function to some of the higher end models (iMac 5k, Apple trashcan, etc.) . See the link below. Be sure to click on "Read all the replies".

Anyway for monitoring and color critical work you will "always" need a third party video interface to get a proper REC.709 video signal or you really work blind. The HDMI connectors on GPUs are meant for computer monitors and therefore they will output a completely different signal. I know most people here don't use a color accurate workflow but for me it makes a huge difference to actually see what I'm doing in Adobe or DaVinci Resolve.

https://discussions.apple.com/thread/6811302?tstart=0

Thanks Daniel, your reply and the link you sent for the Apple forum make things very clear. I have ordered the Black Magic card - which will give me a good working HDMI signal for the time being and allow me to upgrade to a more accurate 4K monitor when the time comes. Great information. Much appreciated.