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- Meet Polaris and the Radeon RX 480
- Using WattMan for overclocking
- Support for VR, DirectX 12 and Vulkan
- Testing the RX 480 in 6 benchmarks
- RX 480 power draw
- RX 480 heat generation
- Stacking up against Nvidia GPUs
- Radeon RX 480: the bottom line
Using WattMan for overclocking
AMD typically reserves new features for its yearly flagship software launches, but it’s rolling out a great new tool alongside the RX 480: AMD WattMan. WattMan’s essentially a supercharged version of the OverDrive overclocking tool AMD has included in its control panel for a while now, with some cool new capabilities and a highly unfortunate name that brings old Sony Walkman cassette players and crappy superheroes to mind. Seriously—who thought WattMan sounded better than OverDrive?
If you’re the overclocking type, WattMan (found in Gaming > Global Settings > Global WattMan) delivers everything you need to tweak your RX 480’s power limit, fan-speed minimums and maximums, target-temperature minimum and maximums, GPU and memory clocks, and individual GPU and memory voltage levels. It’s pretty comprehensive, and AMD took things one step further with the introduction of GPU frequency-curve controls, which let you customize the overclocks for various dynamic power management states (DPMs).
The RX 480 ships with a default frequency curve that affects clock speeds across the various DPMs, and you can apply an overclock by increasing that curve by a set percentage. Alternatively, you can manually set the overclock limits for each DPM using AMD’s new dynamic GPU frequency curve controls. That will let you tailor the overclocking profile to better fit your specific GPU’s potential, but the lack of an automated tool to find your card’s limits may restrict its usefulness in real-world scenarios. (To be fair, there are scanning tools to find your GPU’s limits for the Nvidia’s GTX 10-series cards, but they’re buggy as hell all and irritating to use.)
Increasing the power limit is vital to the RX 480 overclocking process, AMD representatives said. You can boost the RX 480’s power limit by up to 50 percent.
You’ll find another handy tool at the top of the “Global WattMan” settings page in the form of a histogram that tracks your card’s current peak and average GPU activity, temperature, fan speed, and engine/memory clock speeds, and then displays the results as a graph over time. Studying the histogram can really help you hone in on how your card’s behaving, which is crucial to the overclocking process. Per-game histogram tracking can also be enabled in the new “Profile WattMan” tab in your profiles.
Dorky name aside, the new WattMan tools, combined with the existing per-game overclocking options in the Radeon Settings app, provide GPU tweakers with a seriously robust, easy-to-read set of tools for boosting game performance across the board or in specific games. It’s wonderful to see what Radeon Settings, AMD’s sleek new control panel, is evolving into.
Unfortunately, our test system was afflicted by an issue that prevents us from being able to include overclocking results in our performance section. We managed to push our card to a five-percent simple frequency increase on the GPU clock, or a 1,335MHz max, which AMD engineers said was higher than their own sample. We also eked out an additional 150MHz in memory clock speeds.
But applying the overclock actually caused performance to decrease, sometimes drastically. The more we increased the power limit, the worse performance became, no matter how high we cranked the fans or fiddled with temperature settings. The Global WattMan section also appeared to have some stability issues, infrequently crashing the entire Radeon Settings app when we opened it.
AMD engineers speculate the performance hiccup could be an issue with our motherboard’s power delivery, but there was no way to get a new mobo set up in time for testing. For what it’s worth, I’ve overclocked dozens of cards in this system without issue, and I heard from other reviewers who ran into similar problems with performance decreases during overclocking. AMD says its engineers and many other reviewers hadn’t run into the issue, however, so your mileage may vary.
Don’t let our bizarre technical hiccups ruin your impression of this seriously slick, horribly named tool though. I dig it a lot—if it works.
Support for VR, DirectX 12 and Vulkan
While WattMan may be the only high-profile new addition to join existing Radeon features like support for stutter-free FreeSync displays and the surprisingly potent Frame Rate Target Control, AMD’s also loaded the RX 480 with everything needed to support the next generation of gaming goodies. Namely, virtual reality and cutting-edge “close to the metal” graphics APIs like DirectX 12 and Vulkan.
“Bringing virtual reality to the masses” is the big marketing hook AMD’s using to push the RX 480. It feels a bit weird, since the Oculus Rift and HTC Vive are still new, niche gadgets with $600 to $800 price tags that are anything but mainstream. AMD’s $200 card helps make the PCs you need to power the headsets much more affordable, at least. Think of it as laying the groundwork for wider adoption down the road.
The Radeon RX 480 delivers the raw firepower needed to certify as “Capable” in Valve’s SteamVR performance test, but the VR readiness doesn’t end there. AMD says the card offers lower latency and smoother overall frame times. That will pay dividends in traditional gaming and is doubly important to maintain a feel of immersion in VR. If frame rates start sputtering in VR, you’ll start spewing in real life. The 8GB of RAM in the $240 version helps ensure games that gobble up memory will stay smooth, too.
Another key weapon in the Radeon RX 480’s VR arsenal is its dedicated asynchronous compute engine (ACE) hardware. If your card does have trouble maintaining smooth frame rates in a VR game, the Oculus Rift uses a technique called “Asynchronous Timewarp.” Asynchronous Timewarp checks your headset’s position right before displaying an image, and if your head position has moved since the last frame was rendered, Timewarp will adjust the image slightly to match your current orientation. It reduces judder and keep you from hurling.
The GCN architecture that Polaris is based on includes ACEs that basically act as traffic cops, directing myriad graphics tasks to take best advantage of all available Radeon graphics resources simultaneously, rather than using a queue-based “preemption” approach that forces the GPU to complete one task before moving on to another. ACEs let Radeon GPUs do more things at the same time—like performing Asynchronous Timewarp calculations without disrupting the main graphics pipeline.
AMD recently added a new API for its ACEs. Dubbed Quick Response Queue, it allows developers to flag specific tasks—such as the aforementioned Timewarp—as high priority. The GPU’s ACE hardware then assigns high-priority tasks ahead of normal tasks, so time-critical functions get the quick attention they deserve while standard tasks continue to process, albeit with fewer resources.
Here’s an AMD-supplied diagram that illustrates how asynchronous compute, standard preemption, and the new Quick Response Queue behave.
The Radeon RX 480’s ACE hardware can also deliver big benefits in the latest games, just now trickling out, that tap the all-new DirectX 12 and Vulkan APIs. ACE delivers even more benefits with titles that lean heavily on both your processor and your graphics card—strategy games, for instance—and in situations where your graphics card significantly outclasses your CPU.
You’ll see the benefits materialize in our Ashes of the Singularity DX11 vs. DX12 benchmarks later. Meanwhile, this AMD-supplied benchmark shows how Dota 2 behaves in DX11 vs. its beta Vulkan mode. (Vulkan rose from the ashes of AMD’s aborted Mantle API.)
Nvidia’s new GTX 10-series cards include several new features designed to improve asynchronous compute performance, but until more DX12 games start hitting the market, we won’t be able to thoroughly compare the Nvidia and AMD implementations. AMD’s ACE hardware gave AMD a solid boost over GTX 900-series cards in Ashes of the Singularity.
But enough chit-chat. Let’s throw some games at AMD’s first Polaris-based graphics card.
Next page: Testing the AMD Radeon RX 480
AMD Radeon RX 480 (8GB)
AMD's first graphics card built around its cutting-edge Polaris GPU delivers big performance and better power efficiency for just $200, or slightly more for an 8GB version.
- Dirt-cheap price
- No-compromises 1080p gaming, good 1440p gaming
- Can power virtual reality headsets
- Big leap in power efficiency over past AMD cards
- Still not as power efficient as GeForce cards
- Stability and performance issues with slick new overclocking software
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