's a thread with some info on the subject if you're interested.
The Sapphire one listed in that thread is for regular DisplayPort to dual-link DVI. Sapphire also has an active mini DisplayPort version (For single link DVI) that'll work on your setup. That one doesn't require USB power either. I used one of those with my 7950, which worked well. It's one of these
EDIT: Also, you can't go from an adapter like that over to VGA. You'll have to use DVI from the adapter to your monitor since the adapter only supports DVI-D, which is DVI without the analogue signal that VGA uses. Just figured I'd mention that since you originally were trying to use VGA.Edited by Playback - 10/3/13 at 5:32am