EMZETT.DP (DisplayPort)
Photo: In short: A digital connection standard for video (and optionally audio), mainly widespread on PC monitors, technically similar to HDMI in many respects.
In more detail: DisplayPort often supports higher refresh rates at high resolution than comparable HDMI versions, and is therefore often preferred for gaming monitors. Via “multi-stream transport”, several monitors can also be daisy-chained from a single DisplayPort output.
In Depth
Origin: a royalty-free alternative to HDMI
DisplayPort was developed by a manufacturer consortium (VESA — Video Electronics Standards Association) as a royalty-free alternative to HDMI, which was originally more geared towards the consumer electronics market (TVs, Blu-ray players) and charges licensing fees per installed port. As a result, DisplayPort has mainly become established in the PC and monitor space, while HDMI dominates on TVs and consoles — technically, both standards today transmit similarly high resolutions and refresh rates, with a slight time lead one way or the other depending on the current standard version (DisplayPort is usually slightly ahead in maximum bandwidth).
Multi-Stream Transport (MST)
A special feature of DisplayPort is “Multi-Stream Transport” (MST): a single DisplayPort output on the graphics card can drive several monitors at once through it, connected either directly in series (daisy-chain, if the monitors have a DisplayPort output for looping through) or via an external MST hub — all connected monitors share the available bandwidth of the one output, which can become the limiting factor with several high-resolution monitors at a high refresh rate.
DisplayPort over USB-C
Via “DisplayPort Alt Mode”, the DisplayPort signal can also be transmitted over a USB-C connector, which on modern laptops enables driving an external monitor over a single USB-C cable (often combined with power delivery via USB Power Delivery and normal data transfer over the same connector). This is why a single USB-C cable between a laptop and a docking station can transmit video, data and charging current at the same time.
Version history and bandwidth
As with HDMI, DisplayPort also has several version generations with rising bandwidth: DisplayPort 1.4, for example, supports 4K at 120 Hz or 8K at a lower frame rate (with compression), DisplayPort 2.0/2.1 further considerably increases the maximum bandwidth and is designed for future, even higher resolutions and refresh rates. As with all digital video standards: the cable, graphics card and monitor all have to support the same version for the full potential to actually be usable.
Display Stream Compression (DSC)
To transmit very high resolutions and refresh rates (e.g. 8K at 60 Hz or 4K at 240 Hz) even with limited cable bandwidth, newer DisplayPort versions use “Display Stream Compression” (DSC) — a visually near-lossless, but genuine compression of the video signal directly in real time. Unlike with video files, DSC is deliberately designed so that compression artefacts are practically imperceptible to the human eye, allowing considerably higher effective data rates over the same physical cable bandwidth than would be possible uncompressed.
Adaptive sync over DisplayPort
DisplayPort was the first widely used standard to anchor an open, vendor-independent version of adaptive synchronisation (VESA Adaptive-Sync) in the standard itself — the technical basis AMD’s FreeSync is built on. Nvidia’s G-Sync long used proprietary additional hardware in the monitor, but now also supports the open Adaptive-Sync standard via DisplayPort, which has made the previously strict separation between FreeSync and G-Sync monitors considerably more permeable in practice.
See also: HDMI, Monitor, USB-C, Graphics cards