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AMD's Radeon Software Crimson Edition: an overview

Seeing red

AMD's last major update to its graphics driver package, Catalyst Omega, added more than 20 features and fixed more than 400 bugs for Radeon owners. Catalyst Omega also turned on FreeSync and Virtual Super Resolution, features that are now household names. AMD also promised that Catalyst Omega would be the first in a series of annual major updates that would add new features and refinements to the company's driver software.

True to its word, AMD's second major Radeon software release is here—but Catalyst is no more. The company's driver packages will now be called Radeon Software, and Radeon Software Crimson Edition is the first release under the new name.

Crimson (as I'll call it from here on out for brevity's sake) is more than a rebranding exercise, though. This release offers 12 new or improved features, up to 20% higher performance, and tools to eke more efficiency out of AMD graphics cards. Alongside the major driver update itself, AMD is introducing a new management utility called Radeon Settings.

AMD boasts of this software's all-new user interface, better UI performance, improved in-game performance, and higher power efficiency. Those are some ambitious changes, and we'll see whether AMD accomplished everything on its to-do list with Radeon Settings in a moment. For now, let's see what Radeon Software Crimson has in store for those with the red team's graphics cards in their PCs.

What's new
If we were to sum up AMD's goal for Crimson in one word, it'd probably be stability. The company says it ran twice as many automated test cases and 25% more manual test cases during QA on Crimson. It also claims to have tested Crimson on 15% more system configurations, including "the latest technologies."

AMD also polled the community of Radeon users for their top 10 most annoying bugs, and it claims to have fixed those issues in the Crimson release. Some of the more galling problems that the community brought to light included GTA V crashes on Radeon R9 390X cards, errors related to driver installation on systems with Radeon R9 380 cards, and a Diablo 3 crash in the Desolate Sands area of the game.

FreeSync has learned some new tricks in Crimson. AMD has enabled support for FreeSync on CrossFire multi-GPU configurations running in DirectX 9 mode for the first time. FreeSync also gets some polish in certain corner cases where the display isn't receiving frames faster than its minimum refresh rate.

In that situation, and with v-sync on, a feature called low framerate compensation (LFC) will prevent both tearing artifacts and motion judder. With v-sync off, LFC will reduce (but not eliminate) tearing and judder. LFC will only work on FreeSync displays where the maximum refresh rate is greater than or equal to 2.5 times the minimum refresh rate.

Crimson is also the first public driver release with AMD's LiquidVR developer tools enabled. LiquidVR gives devs access to tools like affinity multi-GPU, direct-to-display, latest data latch, and asynchronous shaders. LiquidVR is ultimately meant to let devs create a smoother, more immersive VR experience.

Performance and efficiency improvements
Shader Cache is a Crimson feature that's meant to reduce level load times by storing compiled shaders in a cache on the system's hard drive, a technique that could cut load times up to one-third compared to older driver versions.

Shader Cache could also improve frame time consistency in some cases. We should point out that AMD reached that conclusion by calculating the standard deviation of frame times in its data, a method we don't recommend.

Frame pacing improves frame-time consistency for graphics cards in CrossFire configurations, and it first made its debut a couple years ago with a driver update for the Radeon HD 7990. That feature gets extended to games running in DirectX 9 mode in Crimson, and to demonstrate its benefits, AMD provided the impressively smooth frame-time graph above. Frame pacing for DX9 could help reduce CrossFire-related microstuttering for popular e-sports titles like League of Legends and Dota 2.

Another change—and potential improvement—for e-sports players is an optimized flip queue size.  The Crimson drivers can make use of only a single frame buffer in games where the additional input lag generated by triple-buffering doesn't make sense, like League of Legends or Dota 2. For an idea of where this optimization takes place, have a look at our handy, if oversimplified, diagram of the frame production process:

Moving to a single buffer, as AMD's example above shows, can reduce input lag to 16.7 ms on a 60Hz display, versus 50 ms with triple-buffering enabled. AMD says this improvement makes mouse and keyboard input more responsive. We don't see a per-application setting for the flip queue size in Radeon Settings, so we're guessing that Crimson manages it automatically.

Radeon owners may also see improved performance in general from Crimson. In a best-case scenario with an AMD Radeon R9 Fury X and Crimson, the company says it achieved a 20% improvement in average FPS with the Fable Legends DirectX 12 benchmark running at 1080p. The company's base results were collected with Catalyst 15.7.1 drivers. We put these numbers to the test using our own Fury X at the same settings and with the same software. Here are our results:

The numbers above are certainly a big improvement over Catalyst 15.7.1. For our own curiosity, we collected a third set of results with Catalyst 15.11.1 at similar settings, and we saw average FPS and frame-time numbers similar to the ones we collected with Crimson. It seems that whatever magic is present in Crimson is also in the wild already with Catalyst 15.11.1. Still, it's good to see that AMD can extract additional performance from its graphics cards with software updates, as we've suspected in our past reviews.

Efficiency is another major theme of the Crimson release, and the road to AMD's claimed efficiency increases is Frame Rate Target Control, or FRTC. FRTC is supposed to help reduce power consumption when frame rates would otherwise rocket into the multiple hundreds of FPS, like menus and loading screens.

To curb these apparently wasteful situations, FRTC can be set to cap frame rates at anywhere from 30 FPS to 200 FPS, and it can be configured as a global setting or on a per-application basis. With FRTC on, AMD says Crimson can reduce system power consumption up to 1.8x. FRTC works with DX9, DX10, and DX11 games under Crimson.