I have this card, ATI Radeon HD 5700. Trying to hook up my LG TV using a display port adapter. So when I go to display settings, my monitor is found and shown with the 3 screens. So when I click on my TV and try to extend the display I get an error stating 'Unable to save display settings'. Please advise me on what I should be doing.

From the error message that you are getting it sounds like you have an incorrect cable set up for that video card.

You are only allowed to have 2 legacy connections. These connectiosn are DVI, VGA, HDMI. The third monitor must be connected via Display port. If you do not have a display port monitor you must use an ACTIVE adapter that goes from Dispaly port to DVI/VGA.

Ensure that everything is connected properly and that you have an operating system that is Windows Vista or higher.

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Here is a video to help with the explanation.

http://www.youtube.com/watch?v=Jf0X0lNFmgw&list=PL6CFEA6C71BB14979&index=3&feature=plpp_video

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The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and typographical errors. Links to third party sites are for convenience only, and no endorsement is implied

I can't tell whether or not if this is a active cable, I think my problem is that the display port adapter I have isn't active.  I have had a monitor that has worked in the past, a very old one using the display port adapter.

http://www.pcworld.co.uk/gbuk/advent-adphdm12-displayport-to-hdmi-cable-1-8-m-12818491-pdt.html#longDesc

Do you know if the cable above would work?