AMD Radeon RX 480

In the time that it took to get sick, get better, learn about the Radeon RX 480 power draw issues, write about those same issues, badger AMD and the PCI-SIG engineers for answers, and start writing up a final analysis detailing the whole saga, AMD has gone from acknowledging the issue to having a driver ready to download that more or less fixes it. Either AMD is moving at an unprecedented speed for supporting a new GPU release, or I’m still slow and groggy from the antihistamines I’ve been taking. Hit the jump for more.

Radeon RX 480 power draw fixes

The latest version of Radeon Software Crimson, which is AMD’s codename for their driver releases under the Crimson fork for the current year, is 16.7.1 in beta form (aka a hotfix). It rolls in one important fix to an issue that got a lot of users suddenly interested in PCI-E 3.0 electrical standards, which was that the card would overdraw current from the 12V rails provided by the motherboard. Instead of a maximum of 75W combined from the 12V and 3.3V rails, as it is currently, reviewers were seeing upwards of 80W, sometimes even 95W drawn from the 12V rail alone.

w31080p-all

Above is a graph generated by PC Perspective’s tests on their test bed, where the RX 480 at stock speeds was overdrawing on the PCI-Express bus by around 5 watts on the 12V rail, while also drawing a similar load on the auxiliary 6-pin power connector (quite unusual in itself, as most graphics cards do not load up on the rails in this way). Overdrawing by 5W isn’t worrying for single-card systems. It’s a minor amount over the specification and doesn’t introduce a lot of extra heat for the motherboard to deal with.

w31080p-oc-all

Once overclocked, power draw went up dramatically, in some cases peaking to as much as 95W drawn from the 12V rail on the PCI-E slot (for reference, the standard imposes a limit of 66W from the slot). This is quite worrying. In its bid to keep a 6-pin power connector on the card, AMD designed their PCB to be able to equally load up the 12V rails from both sources in the system, and it didn’t factor in any kind of weighting to tell the voltage regulator which source to draw more power from.

As it turns out, the reference board is designed to cycle load from the auxiliary source and the PCI-E slot, switching from one to the other to minimise heat building up on the connectors. With multiple RX 480s, you might be inviting more danger than reasonable, especially if you’re overclocking them.

w31080p-all-compat

With the new Crimson 16.7.1 driver, there are two power draw fixes available. One is built into the driver, where the driver changes the firmware of the voltage controller when booting the OS, in real-time, to prefer overdrawing from the auxiliary power from the PSU, which is evident in the blue line drawing over 80 watts most of the time, while the white line is now within spec below 66W. These results were also achieved with a special compatibility mode turned on, which is available in the AMD Wattman menu. It’s there for users of older motherboards that might not have their over-current protection mechanisms working, or for users of cheaper boards that didn’t work properly in the first place.

While this fixes the vast majority of issues for most gamers playing modern titles like The Witcher 3, there are still scenarios where the RX 480 will overdraw on power to meet a certain load. With Crimson 16.7.1 installed the power draw issues of the RX 480 aren’t as high as before, but it’s still a cause for concern when you use two or more cards in a system. If that’s you plan, don’t buy the reference designs – wait for the custom boards with 8-pin connectors and better VRMs and voltage management before you take the leap. And by that time, Geforce GTX 1060 cards might be out in the wild to give you a suitable alternative.

Radeon Crimson 16.7.1

The latest version of AMD’s Crimson drivers have added in changes for the Radeon RX 480 power draw issues, and also include the new compatibility mode toggle to further reduce power consumption. There are small improvements for Total War: Warhammer, Metro: Last Light, The Witcher 3 and Far Cry 4, usually totaling around 3% more frames per second.

Resolved issues:

  • Radeon RX 480 limited PCI-E Bandwidth is not at the correct speed on the Radeon RX 480.
  • Minor stuttering occurs in Grand Theft Auto V on Radeon RX 480.
  • Video corruption observed in DOOM with resolutions set above 1920 x 1080.
  • Hitman graphical corruption occurs when the game is set to use DirectX 12 API and using zoom with weapons.
  • Display exhibits minor flicker on Radeon RX 480 when Freesync is enabled on a games launch or exit.

Known issues:

  • A few games may fail to launch or crash if the AMD Gaming Evolved overlay is enabled. A temporary workaround is to disable the AMD Gaming Evolved “In Game Overlay”.
  • Battlefield 4 may experience crashes when using Mantle. As a work around users are suggested to switch to DirectX11.
  • Radeon Pro Duo users may experience a black screen in Total War: Warhammer with the game API set to DirectX 12 and V-Sync enabled.
  • DiRT Rally may experience flickering terrain in some races when the advanced blending option is enabled in the games settings page.
  • Some Overdrive settings may not appear in Radeon Settings for Radeon Fury X when in AMD Crossfire mode.
  • DOTA2 may crash when using the Vulkan API and the user changes resolutions or quality settings.
  • Frame Rate Target Control gaming profiles may fail to enable for some games.
  • Need for Speed may experience flickering on some light sources in AMD Crossfire mode.
  • Frame Rate Target Control gaming profiles may fail to enable for some games.
  • Radeon Wattman may retain settings of an overclock after it has failed. Reset your overclocked settings to fix this temporarily.
  • Low frame rate or stutter may be experienced Wolfenstein: The Old Blood on Radeon RX 480.
  • Assassin’s Creed: Syndicate may experience a game crash or hang when in game settings are set to high or greater.
  • Disabling AMD Crossfire mode on Radeon RX 480 may disable the device in Windows Device Manager. A workaround is to reboot the system to re-enable the device.

Download ’em: Windows 7 SP1, 8.1, and Windows 10 64-bit, Windows 7 SP1, 8.1, and Windows 10 32-bit

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