AMD Radeon R9 285 Graphics Card

A new GPU for the sub-£200 market

You may know that the high-end Radeon R9 290X and R9 290 GPUs use the latest Hawaii GCN 1.2 architecture, imbued with better geometry throughput, tidier design and a general clean-up of the memory controller and back-end when compared to other mainstream Radeon models powered by the first-generation Tahiti architecture. Further improvements stretch to integrating the CrossFire XDMA engine - so no need for external connectors - and adding True Audio support.

But in the context of other premium GPUs, the AMD graphics department has been drinking liberally from the bottle named Rebrand. Let's take the upper-mainstream Radeon R9 280 as an example. Available in March of this year but in fact based almost exclusively on the Radeon HD 7950 graphics processor debuting in January 2012, it's high time AMD evolved the GPU stack and offered consistency from top to middle.

So with the enthusiast segment taken care of by the GCN 1.2 architecture, AMD is shifting this more efficient design down to premium/mainstream levels. The first implementation of this silicon comes in the form of the Radeon R9 285, offered at $250 and thus supplanting the Radeon R9 280. We line the readily available R9 280X and soon-to-be-retired R9 280 against the new pretender.

Analysis

AMD has taken the range-topping Hawaii architecture powering the R9 290(X) GPUs and cut it down to meet the needs of the $250 market. The R9 285 draws similarities with the R9 280; both have an identical engine room - the same number processors, texture units and ROPs - but part of the the back-end is trimmed by reducing the memory interface to 256 bits. The die size and transistor are a touch larger than the Tahiti-powered GPUs, and this is a little surprising given that AMD has limited the bus width on the Tonga silicon.

A consideration of the frequencies shows R9 285 to have about as much shader power as the R9 280 (Radeon HD 7950 Boost, in other words) yet considerably less memory bandwidth, which is an important factor once lots of pixels are thrown around. Making matters worse, on paper at least, the standard memory configuration is reduced from 3GB to 2GB. The new GPU, therefore, is hamstrung in the memory department when compared against its predecessor.

Shouldn't this be slower?

It would perhaps be sensible to imagine the R9 285 being slower than the card it replaces, especially at higher resolutions accompanied by lots of eye candy, but AMD is banking on the efficiencies of the Tonga/Hawaii architecture to come to the fore and mitigate on-paper losses.

In particular, Tonga claws performance back by utilising a much-improved geometry/tessellation setup at the front-end of the GPU and ameliorates the memory-bandwidth advantage, in some cases, by storing colour data in a lossless format, leading to, AMD says, 40 per cent higher memory-bandwidth efficiency in some tests. So while the raw numbers don't look quite as impressive as R9 280, real-world performance should be fairly close, with exact performance differential dependant upon the game engin

We find the Radeon R9 285 interesting because, for the first time, we can reasonably compare the two GCN architectures side by side. The $250 (£170) price point brings Nvidia's GeForce GTX 760 processor very much into play, deliberately so, and all cards bunched in this area need to excel at providing super-smooth gameplay at a 1080p resolution.

AMD contends that anyone looking to upgrade their present graphics card in order to play the latest games at a full-HD resolution with eye candy turned to maximum ought to take notice of the Radeon R9 285. In a strange move, AMD already announced the GPU last week, and Sapphire, amongst others, has been quick in getting a retail model out of the door. Here is the Radeon R9 285 Dual-X OC.

A retail card

Sapphire knows the R9 285 GPU requires less cooling than the R9 280 that has been doing the rounds of late. Thinking about overclocking and ensuring that higher TDPs are catered for, the same Dual-X cooler is repurposed from that model and used here. Measuring 10.5in (262mm) long and presented in the usual dual-slot form factor, Sapphire also includes thermal pads for the memory chips and, probably more importantly, has a small heatsink covering the VRM components situated directly below the right-hand fan.

Summary

AMD, then, is making a sideways move in the upper-mainstream market. Benchmarks from leading websites show that the Tonga-powered Radeon R9 285 performs and costs about the same as the Radeon R9 280 it replaces, but improves upon it by baking in True Audio support and, to a lesser degree, software CrossFire. For £170 you receive excellent 1080p performance from a GPU that's faster than the competition from Nvidia.

As always, Scan Computers is selling a wide range of AMD Radeon R9 285 graphics cards. Please head on over to here to peruse our selection.