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AMD Radeon R9 285 review: The GCN 1.2 torpedo that takes out Nvidia's GTX 760

AMD is launching its new R9 285 today, a killer GPU intended to knock Nvidia out of the $250 price bracket. The new card packs a whallop -- as well as new features we haven't seen on GCN-based cards before. Is this GCN 1.2?
By Joel Hruska
Radeon graphics card, arty, black, R9 285

Ever since AMD launched the Hawaii family of GPUs (R9 290 and R9 290X) the company has maintained a bifurcated structure. Certain features, like TrueAudio and the new superior XDMA engine for Crossfire support have been present on some GPU models but not on others. Today, AMD is launching a new 28nm GPU (codenamed Tonga) and formally known as the R9 285. This new card takes Hawaii's superior feature set and brings it down to the $250 price point -- but then layers on new features of its own. Unofficially, Tonga appears to be the debut of the GCN 1.2 architecture.

The R9 285 carries an MSRP of $250 and it's openly positioned as a GTX 760 killer. Can AMD deliver on that promise? Let's find out.

AMD Radeon R9 285, R9 280X, R9 280, how they compare

What's new about the R9 285?

First, the R9 285 supports TrueAudio, AMD's superior Crossfire scaling solution, XDMA, and the modified GCN front end that AMD introduced with the Hawaii family. That means eight Asynchronous Command Engines (up from two) and support for four primitives per clock cycle (everything but the R9 290 cards top out at two primitives per clock). AMD claims this will give the R9 285 a huge tessellation performance advantage. Overall, this sure looks like GCN 1.2 (though AMD reminded us that such nomenclature was created by the press; it's not an official designation).

The R9 285's new features are as follows:

Support for 16-bit floating point and integer values. This is advantageous in low power settings, where 16-bit precision is more than good enough. Up until now, AMD simply used 32-bit values for all calculations -- switching to 16-bit in specific contexts will save power and internal bandwidth without noticeably degrading image quality. AMD also notes that this new Tonga GPU supports sharing data between SIMD lanes and has an improved task scheduler. Color compression. Frame buffer data is now stored in a lossless compressed format and the GPU can read and write compressed data. This leads to substantial bandwidth efficiency gains and allows AMD to shrink the memory bus from 384 bits to 256 bits. GCN color compression

Such efficiency gains would normally result in a smaller die, but that's not the case here. The R9 285 has a 359mm2 die and 5 billion transistors, compared to 352mm2 and 4.3 billion transistors for the old Radeon HD 7970/R9 280X. AMD has confirmed to us that the new chip has 32 CUs total (with 28 functional), implying that AMD has the option to bring a new version of the core out if it chooses to do so -- but even the additional CUs don't explain why a GPU with a smaller memory bus is both larger and more dense than its predecessor.

Transistor density

The new die is about 14% more dense than the original R9 280X/HD 7970, but in line with the R9 290X family.

New video decode block. The R9 285 also includes a new video decoder block for full hardware decode of H.264 4K streams. H.264 base, main, and high profile up to 5.2 are all supported. That means the new block can handle decoding 4096x2304 streams at 60 fps. There's also a new fixed function video transcoder unit (VCE) that supports full hardware encoding to H.264, but AMD didn't provide additional details on features or capabilities that distinguish this new unit from previous generation hardware. Next page: Test setup and benchmark results

Test setup

We tested the R9 285 using the brand-new Haswell-E platform. All tests were run at 1920x1080 at maximum detail levels. Antialiasing was set to 8x MSAA when available. Our test platform was Windows 8.1 64-bit running on AMD's 240GB Radeon SSD. We used AMD's 14.3 beta driver for our Radeon cards and Nvidia's 340.52 WHQL driver for the GTX 760.

We'll be comparing primarily against the R9 280 on the AMD side of the equation. Currently, R9 280 cards can be had for as little as $219, but we hear rumors that the card isn't long for this Earth. The R9 285 is dropping in at a higher price -- $249 -- but can it match its cheaper sibling with less memory bandwidth and less RAM?

Company of Heroes 2

Company of Heroes 2 is the acclaimed RTS sequel to 2006's Company of Heroes. It focuses on the Eastern Front rather than the Western Front covered by the first title. We tested the game at maximum detail levels and antialiasing (a specific level couldn't be chosen beyond settings like Medium and High).

Company of Heroes Not a bad start for our Radeon cards; the R9 285 matches the R9 280 despite its smaller memory bus and 2GB frame buffer.

BioShock Infinite

BioShock Infinite is one of the most striking, memorable titles of 2013. While not built on the most advanced engine around, the characters and visual spectacle of Columbia are well worth a visit. BioShock Infinite contains a simple, easy to use benchmark routine that takes the player on a flyby through the floating city.

BioShock Infinite Here we have our first major upset of the day. The R9 285 isn't just competitive with its higher-end cousins, it's 16% faster than the R9 280 and 3% faster than the R9 280x. The GTX 760 puts in a good showing here, slipping past the R9 280, but it falls behind the R9 285.

Hitman: Absolution

Hitman Absolution's built-in benchmark flips the tables on our previous results.

Hitman Absolution Here, the R9 285 falls 16% behind the R9 280, which in turn clocks in 12% below the R9 280X. Clearly the game has a fondness for both VRAM and shaders and is capable of stretching both. Still, even here the GTX 760 and the R9 285 are no more than tied.

Metro Last Light

Metro Last Light is the sequel to Metro 2033 and is based on the novels of Dmitry Glukhovsky. We tested all three cards with SSAA (supersampled antialiasing) enabled, as MSAA is not an option.

Metro Last Light Again, the R9 285 keeps up with the R9 280 family, only losing out to the R9 280X by a whisker. The GTX 760 again brings up last place and can't quite reach the coveted 30 fps mark.

Total War: Shogun 2

Shogun 2 may be an AMD Gaming Evolved title but Nvidia has always done well with it and this is no exception.

Total War: Shogun 2 Here, the GTX 760 ekes out a win over the R9 285. There's still a significant gap between the R9 280 and the R9 280X, but the card from Team Green acquits itself well.

Total War: Rome 2

Finally, we have Total War. We use the default "Extreme" preset because Ultra is capable of making $1500 GPUs cry.

Total War: Rome 2 We don't have figures for the R9 280X in this title but once again, the R9 285 and R9 280 are hanging neck and neck. The GTX 760's 35 fps is respectable, but it's still pulling in last place.

Video encoding

Benchmarks that can take advantage of AMD's new decode/encode block are few and far between right now, but fortunately Sandra's video encode/decode test can give us some salient results. We ran the 1280x720 H.264 conversion test on all three GPUs -- the R9 280, the R9 285, and the GTX 760.

Sandra Video encoding

What's interesting here is that AMD may have been playing catch-up in some regards; the R9 285 is far superior to the R9 280 in these workloads but the gap between the R9 285 and the GTX 760 is rather smaller in two of the three tests. Still, these results do speak to AMD's point -- it appears to have significantly overhauled its encoding engine.

We ran multiple other GPU-centric tests under Sandra to see if the R9 285's memory latency or processing capabilities were significantly different but saw no evidence they were.

A range of OEM R9 285 graphics cardsA range of OEM R9 285 graphics cards

Never Settle Space sweetens the deal

The last component of AMD's R9 285 launch is part of the company's software strategy and ongoing Never Settle promotional series. Buyers who opt for an R9 285 or any of the participating R9 cards will get to pick Star Citizen, Alien Isolation, or one of the several dozen other titles that already comprise the Never Settle bundle. Customers who choose Star Citizen will also gain an Omega Variant Racer, access to the multiplayer module, and the Murray Cup Race Series.

Next page: In conclusion, the R9 285 is a fantastic graphics card

R9 285 pummels GTX 760, GCN 1.2 support points the way to Skybridge

There are several key takeaways from this latest launch. First, AMD has flung down a proverbial gauntlet in the $250 space, taking the fight to Nvidia -- with a vengeance. I'm not saying it's anything like a knockout blow -- if there's one thing you can bet on this space, it's that the other guy will have a counter -- but it's a clear challenge and a strong product. Rumors are pointing to a big Nvidia release later in September, incidentally.

Second, it's clear that the improvements to the R9 285 have largely evened the playing field between it and the R9 280, despite the smaller frame buffer and memory bus. When AMD announced the specs on the product I was concerned it would be little more than a cut-rate R9 280. That's not the case.

Third, and most interesting for AMD's long-term roadmap, this new GPU almost certainly represents a GCN 1.2 part, with enough new features to warrant the unofficial title.

GCN architecture

With Tonga, AMD is moving to incorporate specific updates and changes to its core architecture, just as it did with Bonaire and the Radeon HD 7790 back in 2013. When I asked if this meant the R9 285 should be considered GCN 1.2, AMD reminded me that the entire idea of labeling GCN releases with point updates is something the press invented and not the company's preferred way of accounting for its iterative improvements.

That's a fair and accurate point, but we've got to call the chip something and under the circumstances, GCN 1.2 seems appropriate.

Radeon R9 285 So why is AMD releasing an iterative new architecture now, with a transition to 20nm (supposedly) and a possible significant overhaul (GCN 2.0) on the way? I'm guessing it has to do with Project Skybridge. Next year, AMD will unveil a new platform for its 20nm Puma+ and upcoming ARM Cortex SoCs. Skybridge will be compatible with both ARM and x86 hardware -- and we already know that Puma+ is going to add HSA support. That implies that the SoC will also need a tweaked GPU implementation, and the low power computing and increased data parallelism that Tonga implements are precisely the capabilities you'd want in a low-power SoC.

Tagged In

GCN 1.2 R9 280 R9 Components AMD

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