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AMD's Radeon RX 480 graphics card reviewed

Star of wonder, star of night

We've been hearing about AMD's next-generation Polaris GPUs for a little over six months now. We knew those chips would have enhanced display output capabilites, and we also knew they would be produced using 14-nm FinFET process technology. Now, the first product to use this new architecture is here. The Polaris 10 GPU on AMD's Radeon RX 480 graphics card isn't a high-end monster like the GP104 chip powering Nvidia's first 16-nm FinFET cards, though. Instead, the RX 480 puts a $200-and-up price tag on VR-ready performance.

AMD sees a great deal of opportunity to regain market share in the $100-$300 graphics card price range, and the RX 480 is the company's first shot at the middle of the enthusiast bell curve. Let's see how it intends to join this battle.

Baby, you're a star
Polaris is actually a pair of chips—Polaris 10 and Polaris 11—that are two takes on the same underlying architecture. Both Polaris 10 and Polaris 11 will be making their way into desktops, but Polaris 11 is a smaller chip that will probably find a home in many more gaming laptops than it does desktop PCs.

width (bits)
Die size
Polaris 11 16 64/32 1024 2 128 ??? ??? 14 nm
Tonga 32 128/64 2048 4 256 5000 355 28 nm
Polaris 10 32 144/72 2304 4 256 5600 232 14 nm
Hawaii 64 176/88 2816 4 512 6200 438 28 nm
GM206 32 64/64 1024 2 128 2940 227 28 nm
GM204 64 128/128 2048 4 256 5200 398 28 nm
GP104 64 160/160 2560 4 256 7200 314 16 nm

As you can see from the table above, Polaris 10 occupies a much smaller footprint than Tonga before it. Despite its smaller area, Polaris 10 has a bit more of almost everything on board: more stream processors, more texturing units, two times the L2 cache of older chips at 2MB, and a variety of neat tricks that we'll discuss momentarily.

Source: AMD

The block diagram above should be largely familiar to anybody who's laid eyes on AMD's past GCN chips. Polaris 10 has 36 GCN compute units for a total of 2304 stream processors. It has 144 texturing units, four geometry engines, 32 ROPs, and a 256-bit path to GDDR5 memory. From a pure resource standpoint, this part falls somewhere between Tonga and Hawaii in the AMD pantheon.

Source: AMD

Polaris 11 is, at a glance, a little less than half of Polaris 10. It has half the ROPs, less than half of the shaders, half the triangles per clock, and a memory bus that's half as wide. It also has 1MB of L2 cache. It'll almost certainly be smaller than Polaris 10's 232-mm² die, and AMD further notes that this chip is its thinnest GPU ever. That may sound like a weird claim to make, but it's important for achieving the kind of console-class gaming experiences in thin-and-light notebooks that AMD wants to deliver with this architecture. Aside from one desktop card, we don't really know where Polaris 11 will land or what names it'll carry yet. The spotlight is on the Radeon RX 480 for today.

Now that we've seen the two basic Polaris parts, let's examine the common improvements that AMD baked into the underlying architecture.