FreeSync and Frame Pacing Get a Boost

AMD has more than just a UI change in store for Radeon users with the new Crimson Edition of Radeon Software.

Make sure you catch today's live stream we are hosting with AMD to discuss much more about the new Radeon Software Crimson driver. We are giving away four Radeon graphics cards as well!! Find all the information right here.

Earlier this month AMD announced plans to end the life of the Catalyst Control Center application for control of your Radeon GPU, introducing a new brand simply called Radeon Software. The first iteration of this software, Crimson, is being released today and includes some impressive user experience changes that are really worth seeing and, well, experiencing.

Users will no doubt lament the age of the previous Catalyst Control Center; it was slow, clunky and difficult to navigate around. Radeon Software Crimson changes all of this with a new UI, a new backend that allows it to start up almost instantly, as well as a handful of new features that might be a surprise to some of our readers. Here's a quick rundown of what stands out to me:

  • Opens in less than a second in my testing
  • Completely redesigned and modern user interface
  • Faster display initialization
  • New clean install utility (separate download)
  • Per-game Overdrive (overclocking) settings
  • LiquidVR integration
  • FreeSync improvements at low frame rates
  • FreeSync planned for HDMI (though not implemented yet)
  • Frame pacing support in DX9 titles
  • New custom resolution support
  • Desktop-based Virtual Super Resolution
  • Directional scaling for 2K to 4K upscaling (Fiji GPUs only)
  • Shader cache (precompiled) to reduce compiling-induced frame time variance
  • Non-specific DX12 improvements
  • Flip queue size optimizations (frame buffer length) for specific games
  • Wider target range for Frame Rate Target Control

That's quite a list of new features, some of which will be more popular than others, but it looks like there should be something for everyone to love about the new Crimson software package from AMD.

For this story today I wanted to focus on two of the above features that have long been a sticking point for me, and see how well AMD has fixed them with the first release of Radeon Software.

FreeSync: Low Frame Rate Compensation

I might be slightly biased, but I don't think anyone has done a more thorough job of explaining and diving into the differences between AMD FreeSync and NVIDIA G-Sync than the team at PC Perspective. Since day one of the G-Sync variable refresh release we have been following the changes and capabilities of these competing features and writing about what really separates them from a technological point of view, not just pricing and perceived experiences. 

One disadvantage that AMD has had when going up against the NVIDIA technology was prominent at low frame rates. AMD has had "variable refresh rate windows" that have varied from a narrow 48-75Hz (our first 21:9 IPS panel) to a much wider 40-144Hz (TN 2560×1440). When you went above or below that refresh rate with your game render rate (frame rate) you would either revert to a non-variable refresh rate state of either having V-Sync enabled or V-Sync disabled, at the users selection. The result, when your frame rate when below that minimum VRR range, was an experience that was sub-par – you either had tearing on your screen or judder/stutter in the animation. Those were the exact things that VRR technology was supposed to prevent!

NVIDIA G-Sync solved the problem from the beginning by doing something called frame doubling – when your in-game FPS hit that low VRR window range, it would double the frame rate being sent to the screen in order to keep the perceived frame rate (to the monitor at least) high enough to stay inside the range. That gave us no effective minimum variable refresh rate range for NVIDIA G-Sync monitors – and for users that really wanted to push the fringe of performance and image quality settings, that was a significant advantage in nearly all gaming environments.

While NVIDIA was able to handle that functionality in hardware thanks to the G-Sync module embedded in all G-Sync displays, AMD didn't have that option as they were piggy-backing on the Adaptive V-Sync portion of the DisplayPort standard to get FreeSync working. The answer? To implement frame doubling in software, a feature that I have been asking for since day one of FreeSync's release on the market. AMD's new Radeon Software Crimson is the company's first pass at it, with a new feature called Low Frame Rate Compensation (LFC). 

The goal is the same – to prevent tearing and judder when the frame rate drops below the minimum variable refresh rate of the FreeSync monitor. AMD is doing it all in software at the driver level, and while the idea is easy to understand it's not as easy to implement. An algorithm monitors the draw rate of the GPU (this is easy from internal trackers) and when it finds that it is about to cross the VRR minimum of a monitor, double the frame rate being sent from the GPU to the monitor. That "doubled" frame is a duplicate, with no changed data, but it prevents the monitor from going into a danger zone where screen flicker and other bad effects can occur. For a visual representation of this behavior (in hardware or software) look at the graph below (though it uses data from before AMD implemented LFC). 

There are a couple of things to keep in mind with AMD's LFC technology though. First, it is automatically enabled on supported monitors and there is no ability to turn the feature on or off manually. Not usually a big deal – but I do worry that we'll find edge cases where LFC will affect game play negatively, and having the ability to turn this new feature off when you want would help troubleshooting at the very least.

Also, AMD's LFC can only be enabled on monitors in which the maximum refresh rate is 2.5x (or more) higher than the minimum variable refresh rate. Do you have a monitor with a 40-144Hz FreeSync range? You're good. Do you have one of the first 48-75Hz displays? Sorry, you are out luck. AMD has a wide range of FreeSync monitors on the market today and they don't actively advertise that range, so you won't know for sure without reading other reviews (like ours) if your monitor will support Low Frame Rate Compensation or not – which could be a concern for buyers going forward. 4K FreeSync monitors which often have a ~32Hz to 60Hz range will not have the ability to support LFC, which is unfortunate as this is one key configuration where the feature is needed! (As another aside, this might explain why NVIDIA has been more selective in its panel selection for G-Sync monitors; even though they frame double in hardware they still need at least ~2x between the minimum and maximum refresh rates.)

I have spent the last couple of days with the new Crimson driver and tested Low Frame Rate Compensation with several FreeSync monitors including the ASUS MG279Q, the ASUS MG278Q, the Acer XR341CK and the LG 29UM67. Of those four displays we have in-house, only the LG 29UM67 has a FreeSync range that is outside the support criteria for LFC and as I expected, the monitor behaved no differently with the Crimson driver than it did with any software before it. All three of the other displays worked though, including the 35-90Hz range on the MG279Q, the 40-144Hz on the MG278Q and the 30-75Hz range on the UltraWide Acer XR341CK. 

Testing the ASUS MG278Q with Low Frame Rate Compensation. Nevermind the cable clutter!

Using an application we have internally to manually select a frame rate, I was able to bring the monitors below those previously tested ranges and the LFC behavior seemed to be working as expected. With the V-Sync setting in the game off, moving to 30 FPS on the ASUS MG279Q did not result in screen tearing of any kind. I was able to go all the way down to 10 FPS and didn't see any kind of visual artifacting as a result of the frame doubling. I duplicated this process with the other two monitors as well – both passed.

Of course I ran through some games as well including Grand Theft Auto V where I could easily adjust settings to get frame rates below the VRR range of the monitors on our Radeon R9 380X test bed. The game was able to move in and out of the variable refresh rate minimum without tearing or judder that would have previously been a part of the FreeSync experience.

That's great news! But there were a couple of oddities I need to report. At one point, with both a Radeon R9 295X2 and the R9 380X, the ASUS MG279Q exhibited some extreme flickering when in the variable refresh rate range and below. This kind of flicker reminded me of the type we saw on older G-Sync monitors when hitting an instantaneous 0 FPS frame rate – the frame rate doubling was influencing the brightness of the screen to a degree that we could pick it up just looking at it. I am not sure if this flickering we saw is an issue with the driver or with the monitor but I only saw it 2-3 times in my various reboots, monitor swaps and GPU changes. 

I will also tell you that the smoothness of the doubled frame rate with AMD FreeSync and LFC doesn't feel as good as that on our various G-Sync monitors. I am interested to get more detail from AMD and NVIDIA to see how their algorithms compare on when and how to insert a new frame – my guess is that NVIDIA has had more time to perfect its module logic than AMD's driver team has and any fringe cases that crop up (Are you just on the edge of the VRR range? How long have you been on that edge? Is the frame rate set to spike back up above it in the next frame or two?) aren't dealt with differently.

Despite those couple of complaints, my first impression of LFC with the Crimson driver is one of satisfied acceptance. It's a great start, there is room to improve, but AMD is listening and fixing technologies to better compete with NVIDIA as we head into 2016.

Frame Pacing: Legacy DX9 Support

It's been nearly three years since we first published our full findings on frame pacing and how it affects gaming experiences in multi-GPU CrossFire gaming configurations. Frame Rating has been our on-going project in that regard ever since and AMD was able to again make significant strides in that area from where it began. When AMD first delivered a frame pacing enabled driver for DX10 and DX11 games in August of 2013, they promised that "phase 2" would include support for DX9 in the future. Well, nearly 2.5 years later, I present to you, phase 2.

This is Skyrim, the last remaining DX9 title that we use in our tests (most of the time), running at 3840×2160 (4K) on the Radeon R9 295X2 dual-Hawaii graphics card. The orange line is a result from an older driver, before DX9 frame pacing was enabled and you can clearly see the effect that AMD's older driver architecture had on gaming experience. That ugly blob of orange on the Frame Times graph shows you the "runt" frames that the GPUs were rendering but not displaying in an even manner, artificially raising performance results and making the gamer's experience a stuttery mess. 

The black line is what we tested with the new Radeon Software Crimson driver – a much more polished experience! Frame pacing is 1000x better than it was before and you can just FEEL the difference when playing the game. Actual user experienced average frame rates jumped from ~90 FPS to ~130 FPS which is a nice improvement at the 4K resolution. Frame time variance on the 95th percentile drops from from about 7ms to 2ms showing in data what playing the game for yourself does – its just so much better than it was before.

This DX9 frame pacing improvement should work across all compatible Radeon GPUs and all DX9 gaming titles, though it's more than fair to say that the number of DX9 games that need CrossFire multi-GPU support is low at this point. I'm glad to see it in there – but it's impact on sales and user goodwill is probably minimal as we hit Thanksgiving of 2015.

Closing Thoughts

These are just a couple of the new features found in the AMD Radeon Software Crimson Edition release. I would unequivocally recommend to users of Radeon GPUs to download and give this new software a download and try it out. It's faster, easier to use, implements performance enhancements for new PC games and makes nearly every facet of the Radeon user experience better.

The formation of Raja Koduri's new Radeon Software Group is just starting but I am impressed with the first new release under his watch. AMD will need more than Crimson to compete with NVIDIA in 2016 though but I have more confidence than ever that it can be done. And I think 2015 still holds a couple of interesting surprises for us to discover together.