Page 25 - Computer Power User - February 2017

FreeSync’s variable refresh
rate capability is based on
Adaptive Sync, which is a VESA
(Video Electronics Standards
Association) industry standard
that was originally designed to
support dynamic refresh rates
over the DisplayPort interface.
By using the existing DisplayPort
protocol, AMD was able to
reduce the complexity necessary
to implement FreeSync into a
display. NVIDIA’s G-SYNC,
by comparison, requires a
chip inside the monitor that
coordinates the refresh rate of
the display. FreeSync’s relative
simplicity reduces cost and
makes it easier for monitor
Vsync fixes one problem (screen tearing) but introduces two others (stutter and lag) in the process.
manufacturers to support
variable refresh rates.
Initially, FreeSync only
Vsync’s effect on input lag is another create FreeSync displays, and in total, there worked over DisplayPort, but in 2016,
concern, because the GPU might have to were 121 FreeSync compatible monitors. AMD developed an extension of FreeSync
hold onto a rendered frame for too long. For AMD expects that most all of the partners to allow for variable refresh rates over
example, the GPU might buffer up to three who built FreeSync monitors will create HDMI. We’ve found that monitors
fully rendered frames until the monitor is FreeSync 2-compatible options. But don’t typically only support FreeSync over either
ready to draw a new on-screen frame. The expect to see the market flood with as DisplayPort or HDMI. And unfortunately,
lag trade-off can make Vsync unsuitable many FreeSync 2 monitors as you did with not all monitor manufacturers have clear
for shooters and other games that require FreeSync monitors, because AMD will have specifications about which display interface
precise, quick action. By perfectly matching strict standards for the minimum brightness, supports FreeSync, meaning you might
the refresh rate of the GPU and monitor, contrast, and color space. To make the cut, a have to dig through your display’s manual
FreeSync and G-SYNC do away with both monitor must be able to meet these standards a bit to discover which port supports
screen tearing and Vsync’s stutter and lag. while also delivering extremely low latency. variable refresh rates.

FreeSync
FreeSync’s dynamic refresh rate
is supported by most Radeon GPUs
released in 2014 or after, which
includes the Radeon R9 290 and R7
260X. Older Radeon GPUs, such as
the HD 7000 and R9 280, support
FreeSync for video playback and power-
saving jobs, but these cards don’t have
a display controller that supports the
transformative adaptive sync capabilities.
GPUs based on AMD’s new Polaris and
upcoming Vega architecture, of course,
support FreeSync. Best of all, AMD says
that any FreeSync-compatible Radeon
GPU will also support FreeSync 2.
As of December 2016, 20 display FreeSync & G-SYNC avoid screen tearing that can occur when Vsync is off.
makers had partnered with AMD to

CPU / February2017 25