The Advantages of Eyefinity for CAD, Part 2: Adapters to the Rescue
It might not seem the most elegant solution, but if you want to use your new DisplayPort card to drive an existing multi-monitor setup or you want to add low cost DVI monitors to complete your Eyefinity system, then you can buy relatively inexpensive DisplayPort adapters.
Active vs. Passive
Ah, if it were only that simple — just buy a DisplayPort adapter and all will work. Actually it is that simple, but until recently, the DisplayPort ecosystem was playing catch-up. You had to pay attention to what kind of adapter: Passive or Active.
The issue arises because DVI/HDMI requires a dedicated clock source per output. On the other hand DisplayPort only requires one clock source to drive as many outputs as supported by the GPU. FirePro cards offer a workaround by including two clocks which means you can simultaneously drive two DVI/HDMI displays from dual-mode DisplayPort outputs using nothing more than a Passive adapter. But to use more than two DVI/HDMI displays, you need to use an Active adapter (a cable or dongle that integrates a DisplayPort translator chip, and a DAC for the VGA case ).
Sounds confusing? Wait it gets a little worse. All of the above only refers to single-link DVI displays (displays that handle up to 1920 x 1200 resolution at 60 Hz). If you are trying to drive dual-link DVI displays with resolutions up to 2560 x 1600 like the HP 30-inch or Apple Cinema Display, then you need a USB bus-Powered Active adapter/dongle.
Let’s Just Keep It Simple
Needless to say, this scenario of two adapters for single-link DVI and a third for dual-link DVI, caused a lot of confusion in the early days of DisplayPort and Eyefinity. Not only could you not use your new graphics card until you ran out and bought adapters. But even with adapters in hand, you could find that you had purchased the wrong type of adapter to drive the third or fourth display. It wasn’t an unsolvable crisis, but it was sure irritating.
Active Adapters Included in the Box
The new FirePro V7900 and FirePro V5900 cards eliminate the Passive vs. Active confusion, as well as the need to buy anything additional. The graphics cards simply come with Active adapters. You don’t need to think if you are connecting your 1st, 2nd, 3rd or 4th monitor. Just plug in one of the included adapters and it supplies the conversion as needed. Simple (almost Apple-esque in the “it just works” simplicity). I hope we see more of this “included in the box” approach.
Of course, if you have a legacy dual-link display, then you still need a special bus-powered adapter. But fewer people have this setup then those with the more common multiple, single-link DVI monitors.
Next I’ll discuss the Rules of Thumb for Eyefinity setups.
Author: Tony DeYoung