Today I got a new Sapphire Radeon HD 4670. I've attached two monitors into the DVI and D-SUB ports and connected my TV into the HDMI port (so essentially three monitors are connected).
So far the card is working perfectly, except for one thing I don't understand. All three monitors show up as potential displays in the "Screen Resolution" menu (I'm running Windows 7 64-bit) but one of them is blacked out, meaning it won't let me use it. More accurately put, it will let me use any two of the three to display/extend my desktop, but not all of them. What could be the problem?
Here's a screenshot from my main display:
I read something on here about something you can buy called a DisplayPort. Would that solve this problem or is there a less costly way?