AMD’s latest graphics card, the Radeon R9 285, uses a brand-new core, dubbed Tonga.
The R9 285 is designed to replace the R9 280 as well as bring the fight to Nvidia’s GeForce GTX 760, and it should play every game at 1080p and 1440p – although 4K will likely be beyond its abilities.
AMD Radeon R9 285: Under the Hood
The R9 285 is the only card to currently use the Tonga core. It’s a mid-range core, but it shares a crucial part of its architecture with AMD’s high-end 290-series parts, with the 1,792 stream processors split into a quartet of shader engines. That means the R9 285 has double the engines of the 280 it replaces – a move that should improve performance in a host of areas, from geometric and tessellation performance to general compute tasks.
Tonga’s high-end DNA bodes well for gaming performance, and that’s not the only impressive statistic inside this GPU. AMD says there are 5 billion transistors inside, which is more than the 4.3 billion inside the R9 280 – and almost 1.5 billion more than Nvidia’s GTX 760 offers. The R9 285 is still built on the familiar Graphics Core Next architecture, but this third iteration has been improved across the board. There’s better support for 4K H.264 video playback, transcoding is more efficient, and AMD says that lossless compression makes for more efficient memory handling.
This card also has the latest CrossFire controller, so multi-GPU setups don’t require bridge connectors – everything goes through the PCI-Express slot. The Mantle API and TrueAudio are both supported, although their advantages will only be obvious when more developers are on-board with both programmes. On the outside the R9 285 doesn’t throw up any surprises. Card length varies depending on which board partner you use, but the R9 285 is a similar length to the R9 280 and GTX 760 – so you’re looking at a 270mm-300mm PCB. The R9 285 requires two six-pin power connectors. This how the one we used looked from the outside.
How We Tested
We’ve locked and loaded five games for this GPU test. Bioshock Infinite and Batman: Arkham Origins to the mix. We’ve tested at 1,920 x 1,080, 2,560 x 1,440 and even 3,840 x 2,160 to see which card is best across single-screens – and to check if any of them can handle 4K.
We’ve used 3D Mark’s Fire Strike test and four Unigine Heaven benchmarks to test theoretical performance, and we’ve taken idle and load temperatures and power requirements to see which card is the coolest and most frugal.
| AMD GPU Specification Comparison | ||||||
| AMD Radeon R9 290 | AMD Radeon R9 280X | AMD Radeon R9 285 | AMD Radeon R9 280 | |||
| Stream Processors | 2560 | 2048 | 1792 | 1792 | ||
| Texture Units | 160 | 128 | 112 | 112 | ||
| ROPs | 64 | 32 | 32 | 32 | ||
| Core Clock | 662MHz | 850MHz | ? | 827MHz | ||
| Boost Clock | 947MHz | 1000MHz | 918MHz | 933MHz | ||
| Memory Clock | 5GHz GDDR5 | 6GHz GDDR5 | 5.5GHz GDDR5 | 5GHz GDDR5 | ||
| Memory Bus Width | 512-bit | 384-bit | 256-bit | 384-bit | ||
| VRAM | 4GB | 3GB | 2GB | 3GB | ||
| FP64 | 1/8 | 1/4 | 1/16 | 1/4 | ||
| TrueAudio | Y | N | Y | N | ||
| Typical Board Power | 250W | 250W | 190W | 250W | ||
| Manufacturing Process | TSMC 28nm | TSMC 28nm | TSMC 28nm | TSMC 28nm | ||
| Architecture | GCN 1.1 | GCN 1.0 | GCN 1.2 | GCN 1.0 | ||
| GPU | Hawaii | Tahiti | Tonga | Tahiti | ||
Final Thoughts
The Radeon R9 285 is a lateral for AMD, and as we’ve seen in our results this is for a good reason. Despite all of the architectural and feature changes between the R9 285 and its R9 280 predecessor at the end of the day it brings a very minor 3-5% performance increase over the R9 280 with virtually no change in price or power consumption. Functionally speaking it’s just an R9 280 with more features.
From a feature standpoint then, Tonga and the underlying GCN 1.2 architecture is a small but nonetheless impressive iteration on what AMD has already done with GCN 1.1.
Having said that, the Radeon R9 285 is a wonderful option at the price and probably represents the best product a gamer can buy for that price, just as the Radeon R9 280. For folks coming from entry-level graphics cards, the Radeon R9 285 is an excellent upgrade choice and delivers true high-detail 1080p gaming.
