Review: AMD Radeon RX 480 8GB – Polaris Finally Arrives!
… Polaris 10 out of 10.
It would be a fair assumption that AMD named its new GPU after one of the brightest stars in the night sky because to them, that’s exactly what this new GPU is. Huge strides have been made in its engineering, including a brand new architecture based on the new Samsung/GlobalFoundries 14nm FinFET process.
Over the past few years, AMD has been making aggressive pushes into the mainstream PC gaming market. With an all-new ad campaign entitled “The Uprising”, which encourages gamers to join the “Radeon Rebellion” – this Rebellion, of course refers to the fact that AMD has decided that instead of debuting an all-new GCN 4.0 architecture with a high-end, top of the line graphics card to challege NVIDIA’s Pascal based GTX 1080 and GTX 1070, they will instead focus on the lower-end mainstream and performance segments first. This is a very strategic move for AMD as mainstream Pascal GPUs are still in the pipeline making Nvidia’s last generation mainstream Maxwell GPUs the only competition for AMD’s latest chips.
To serve those markets, AMD has unveiled three new products – the AMD Radeon RX 480, RX 470 and RX 460. AMD is expected to be releasing the Radeon RX 480 now while the others are set to release at a later date. Very little is known about the Radeon RX 470 and the Radeon RX 460 at this point, but it shouldn’t be too long now that the first chip in the family has arrived.
AMD Radeon RX 480 Specifications
| GPU | RX 480 | R9 380X | R9 390 | R9 390X |
|---|---|---|---|---|
| Codename | Polaris 10 | Antigua (Tonga) XT | Grenada (Hawaii) Pro | Grenada (Hawaii) XT |
| Architecture | GCN 4.0 | GCN GCN 3.0/1.2 | GCN GCN 2.0/1.1 | |
| Fabrication | 14nm FinFET | 28nm | ||
| Core Clock (MHz) | 1266/1120 | 970 | 1000 | 1050 |
| Compute Units | 36 | 32 | 40 | 44 |
| Stream Processors | 2304 | 2048 | 2560 | 2816 |
| Texture Units | 144 | 128 | 160 | 176 |
| ROPs | 32 | 32 | 64 | 64 |
| Framebuffer | 4GB/8GB | 4GB | 8GB | |
| Memory Type | GDDR5 | |||
| Memory Interface | 256-bit | 256-bit | 512-bit | 512-bit |
| Memory Clock | 7/8 Gbps | 5.7 Gbps | 6.0 Gbps | 5.0 Gbps |
| TDP | 150W | 190W | 275W | 275W |
| Launch Price | $199/$239 | $229 | $329 | $429 |
The AMD Radeon RX 480 is claimed to offer performance up to 5.8 TFLOPs with Memory Bandwidth of 224 GB/s or higher. As we can see in the chart above, the RX 480 offers roughly 20% higher reference clock speeds than previous generation Radeon graphics cards while consuming up to ~45% less power. When compared directly to its predecessor, the AMD Radeon R9 380X, we can see a roughly 12% increase in Stream Processors, and an up to 40% increase in memory clocks.
AMD has told us that the reference configuration for the Radeon RX 480 will sport 4GB of 7 Gbps memory, while they will also be shipping models with 8GB of 8 Gbps memory, which is what we’ll be reviewing today. We’ve also been told that while board partners will be offering configurations which vary from these reference specifications, they will always offer memory clock speeds of at least 7 Gbps.
GCN 4.0 Architecture Improvements
With GCN (Graphics CoreNext) 4.0, AMD has improved on a number of areas compared to the previous generations. These changes include improved geometry processing for increased performance in heavily tessellated environments, improved shader efficiency, with up to 15% more performance per CU compared to the R9 290 series, and an updated memory controller along with improved Delta Color Compression, which allows for a higher effective peak memory bandwidth.
The block diagram reveals that Polaris 10 carries 4 ACE (Asynchronous Compute Engines), 2 HWS (Hardware Scheduler) and a single Graphics Command Processor. All of this feeds into the 4x Shader Engines which each include a Geometry Processor and a Rasterizer. Each Shader Engine also houses 9 CUs (Compute Units), for a total of 36.. These CUs share a single 2MB pool of L2 Cache and link directly to eight 32-bit GDDR5 memory controllers, which gives us our 256-bit bus.
The Radeon RX 480 has a few notable changes compared to the Antigua (Tonga) based R9 380X. Firstly, there’s the reduction in ACE from 8 to 4, then the inclusion of these new Hardware Schedulers, which are used for Async Compute. Then, there’s the increase in CUs per Shader Engine from 8 to 9, which changes the total number of Compute Units from 32 to 36. There’s also the increase in memory controllers, from 4x 64-bit to 8x 32-bit. This gives us the same total bus width, but allows for increased maximum memory capacities from 4GB to 8GB without the need for having memory chips on both the front and back of the PCB.
Now for some highlights of the hardware scheduler. We’re seeing an expansion of the capabilities of Async Compute to include features such as real-time and prioritized queues for audio and VR. These new hardware features are targeted by new software APIs in AMD’s LiquidVR.
These new features include TrueAudio Next, Compute Unit Reservation, Quick Response Queue (QRQ) and Variable Rate Shading.
TrueAudio Next, is a the latest version of AMD’s TrueAudio technology. It allows for real-time GPU audio physics processing using both Ray Tracing and Convolution in order to realistically simulate an environments unique audio physics. The sounds of gun shots or glass shattering in a large, empty room will sound very different from the same audio effects in a smaller, crowded room. This allows for much greater immersion in VR games.
Variable Rate Shading essentially allows for games to render different aspects of a scene in different resolutions or quality settings. This allows items at the center of the frame to be rendered in the maximum detail, while those in the periphery will be lower quality. This more accurately simulates how our own eyes work, as we mainly use our peripheral vision to detect motion rather than spot actual details in an image.
Finally, GCN 4.0 also supports the latest display connectivity standards including DisplayPort 1.3/1.4 HDR and HDMI 2.0b. These technologies enable support for higher resolutions, higher refresh rates and full HDR (high dynamic range) support for improved colors on displays that support it.
Now that we’ve got all that out of the way, let’s take a closer look at the Radeon RX 480.
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