The DisplayPort Adaptive-Sync is vendor-neutral and doesn't require any new, specialized hardware like is needed with NVIDIA G-Sync, as long as it's in compliance with the DisplayPort 1.2a specification. Adaptive-Sync has mostly been driven by AMD as a "FreeSync" alternative to NVIDIA G-Sync.
Computer monitors normally refresh their displays at a fixed frame rate. In gaming applications, a computer’s CPU or GPU output frame rate will vary according to the rendering complexity of the image. If a display’s refresh rate and a computer’s render rate are not synchronized, visual artifacts—tearing or stuttering—can be seen by the user. DisplayPort Adaptive-Sync enables the display to dynamically match a GPU’s rendering rate, on a frame-by-frame basis, to produce a smoother, low latency, gaming experience.
In applications where the display content is static—such as surfing the web, reading email, or viewing a slide presentation—DisplayPort Adaptive-Sync allows the display refresh rate to be reduced seamlessly, lowering system power and extending battery life.
During the playback of lower frame rate video content, Adaptive-Sync allows the source to optimize transport of the video format leveraging OS and DisplayPort interfaces. In addition to providing smoother video playback, the lower frame rate enabled by Adaptive-Sync also reduces power demand, extending battery life.
It will still probably be a while before seeing DisplayPort 1.2a systems available for sale, but more information on the VESA-approved Adaptive-Sync can be found via today's VESA.org press release.