As Fast As Possible
AMD FreeSync synchronizes a compatible monitor’s refresh rate (Hz) with a compatible graphics card’s frame rate (FPS). As a result, all screen tearing and stuttering is eliminated within the dynamic refresh rate range of the display.
Update: Added information about new FreeSync branding including FreeSync Premium and FreeSync Premium Pro.
AMD Radeon FreeSync technology uses the Adaptive-Sync protocols of DisplayPort and HDMI connectors to provide a variable refresh rate (VRR) which allows refresh rates of a monitor to change dynamically and in synchronization with frame rates of a graphics card.
What Is FreeSync?
AMD has worked with VESA (Video Electronics Standard Association) to add support for Adaptive Sync into the DisplayPort 1.2a standard, and later HDMI, which they then utilized for their FreeSync technology.
With AMD FreeSync, you will not get screen tearing or visual latency which you typically get from having VSYNC disabled. You won’t get the stuttering and input lag associated with VSYNC enabled either.
To take advantage of the benefits of AMD FreeSync technology, users will require a FreeSync-compatible monitor and a FreeSync-compatible AMD Radeon GPU.
As of 15 January 2019, you can also use NVIDIA graphics cards (GTX 10-series, GTX 16-series, RTX 20-series or newer) with G-SYNC compatible FreeSync monitors.
What Does AMD FreeSync Do?
In order to understand how FreeSync works and what it does, you need to know how a monitor and a graphics card communicate with each other in order to create an image.
In short, the GPU renders the frames and sends them to the display which then refreshes those frames a certain number of times (60 times if it’s a 60Hz monitor, etc) to create the picture.
However, sometimes the GPU will send excess frames to the display whilst the monitor is still displaying the previous refresh cycle. This creates screen tearing (picture below).
You can get rid of screen tearing by enabling the VSYNC option in your drivers or video game settings.
VSYNC forces the GPU to wait until the monitor is ready to display the next frame thus eliminating screen tearing.
Consequently, this introduces additional input lag and if the card cannot render the frames before the next refresh occurs, it will be displayed again which creates screen stuttering.
In the end, you are choosing between no screen tearing at the cost of input lag (VSYNC on) or screen tearing and lower input lag (VSYNC off).
This is where FreeSync kicks in and makes the GPU and the display work in perfect harmony within a certain refresh rate range; the width of that ranges depends on the monitor.
LFC (Low Framerate Compensation)
As long as you are within the dynamic refresh rate range of FreeSync, you will not experience screen stuttering, tearing, or a noticeable increase in input lag. If your FPS (Frames Per Second) rate dips below that range though, FreeSync stops working.
The main problem here is that many FreeSync monitors have a narrow dynamic refresh rate range; for example 48-75Hz or 40-75Hz instead of 30-75Hz for monitors with a 75Hz maximum refresh rate.
It’s possible to increase the dynamic range on some monitors using the CRU (Custom Resolution Utility) third-party software.
Some FreeSync monitors, however, feature the AMD LFC technology which multiplies the refresh rate when your FPS drops below the lower end of the range thus maintaining a smoother judder-free performance.
For example, if your FPS rate drops to 37 FPS, LFC will change the display’s refresh rate to 74Hz on a 75Hz monitor for smoother performance.
All monitors that have a variable refresh rate range of at least 2:1 (for instance 50Hz-100Hz) automatically support LFC. So, if you are looking for a FreeSync monitor, you should look for a wide variable refresh rate range and the LFC support.
AMD FreeSync vs NVIDIA G-SYNC
While G-SYNC displays have a dedicated module installed in them which significantly adds to the price of the monitor, AMD FreeSync adds no extra cost to the monitor. However, G-SYNC monitors usually also have a wider dynamic refresh rate range and lower input lag.
Further, most G-SYNC monitors only support VRR when the monitor is connected to the GPU via a DisplayPort input whereas most FreeSync monitors work over both HDMI and DisplayPort.
Future G-SYNC gaming monitor will actually support HDMI-VRR and Adaptive-Sync over HDMI and DisplayPort. The Acer Predator XB273 X is the first monitor to be announced to support both technologies.
Lastly, G-SYNC monitors support variable overdrive which allows the display’s response time overdrive setting to change on the fly according to the frame rate. As a result, you get no overshoot at low frame rates and no ghosting at high frame rates.
With FreeSync monitors, you have to manually change the overdrive option which can be an issue if your FPS rate often fluctuates in games.