At the end of the day the MST hub is how AMD and other manufacturers are going to drive multiple displays from devices that don’t have the space for multiple outputs.įor Barts AMD is keeping parity with Cypress’s display controller, giving Barts the ability to drive up to 6 monitors. Furthermore MST hubs are compatible with adaptors, meaning DVI/VGA/HDMI ports can be created off of a MST hub by using the appropriate active adaptor.
The importance of this distinction is that the MST hub does away with the need to have a DP1.2 compliant monitor, as the hub is taking care of separating the display streams and communicating to the host via DP1.2. A MST hub splits up the signal between client devices, and in spite of what the name “hub” may imply a MST hub is actually a smart device – it’s closer to a USB hub in that it’s actively processing signals than it is an Ethernet hub that blindly passes things along. The alternative method is to use a DP1.2 MST hub. In practice we don’t expect to see daisy-chaining used much except on prefabricated multi-monitor setups, as daisy-chaining requires DP1.2 monitors and can be clumsy to setup. Daisy-chaining is rather self-explanatory, with one DP1.2 monitor plugged in to the next one to pass along the signal to each successive monitor. Meanwhile on the receiving end there are two ways to handle MST: daisy-chaining and hubs. MST, as the name implies, takes advantage of DP1.2’s bandwidth and packetized nature by interleaving several display streams in to a single DP1.2 stream, with a completely unique display stream for each monitor. For these reasons multiple display support was canonized in to the DP1.2 standard under the name Multi-Stream Transport (MST).
Furthermore because DisplayPort is a packet-based transmission medium, it’s easy to expand its feature set since devices only need to know how to handle packets addressed to them.
DP1.2’s bandwidth upgrade means that it has more than enough bandwidth to drive even the largest consumer monitor more specifically a single DP1.2 link has enough bandwidth to drmonitors or 4 1920 monitors at 60Hz. It’s by doubling DisplayPort’s bandwidth, along with defining new standards, that enable DP1.2’s new features.Īt the moment the feature AMD is touting the most with DP1.2 is its ability to drive multiple monitors from a single port, which relates directly to AMD’s Eyefinity technology.
So what does DP1.2 bring to the table? On a technical level, the only major change is that DP1.2 doubles DP1.1’s bandwidth, from 10.8Gbps (8.64Gbps video) to 21.6Gbps (17.28Gbps video) or to put this in DVI terms DP1.2 will have roughly twice as much video bandwidth as a dual-link DVI port. Instead they’re calling it DP1.2 Ready for the time being.
The Radeon HD 6800 series will be the first products anywhere shipping with DP1.2 support – in fact AMD can’t even call it DP1.2 Compliant because the other devices needed for compliance testing aren’t available yet. So with AMD’s investment in DisplayPort it should come as no surprise that they’re already ready with support for the next version of DisplayPort, less than a year after the specification was finalized.
Furthermore for AMD DisplayPort goes hand-in-hand with their Eyefinity initiative, as AMD relies on the fact that DisplayPort doesn’t require an independent clock generator for each monitor in order to efficiently drive 6 monitors from a single card. AMD has been a major backer of DisplayPort since it was created in 2006, and in 2009 they went as far as making DisplayPort part of their standard port configuration for most of the 5000 series cards. We’ll start on the display side with DisplayPort. Compared to Cypress, practically everything involving displays and video decoding has been refreshed, replaced, or overhauled, making these feature upgrades the defining change for the 6800 series. While Barts doesn’t bring a massive overhaul to AMD’s core architecture, it’s a different story for all of the secondary controllers contained within Barts.