Just before Nvidias’ move with their latest Maxwell-based GTX 970 and GTX 980, AMD has released into the wild a new GPU with the Tonga code name and the cards have received the R9 285 naming. Despite the numbering scheme, the number of shader cores, texture units and ROPs is identical to the Tahiti R9 280 GPU but the memory bus has been shrinked from 384-bit to 256-bit and the onboard memory is now 2GB instead of 3GB. At the default memory frequencies, the memory bandwidth has been lowered from 240GB/s to 176GB/s.

Besides those mentioned, the card is built on the newer GCN 1.2 architecture, has a much lower TDP versus the R9 280 (190W), supports AMD TrueAudio which was only available with the R7 260, 260X and R9 290, 290X cards; one more important thing to mention is that the card does not need a CrossFire finger for operating in multiple cards configurations.

GCN 1.2 instruction set includes an improved compute task scheduling, new 16-bit floating point and integer instructions for low-power GPU compute and media processing but also data parallel processing instructions (sharing between SIMD lanes). Tessellation has noticeable improvements, with Tonga being able to trail Hawaii GPU at low tessellation factors and bringing unexpected performance increase over Tahiti at x64 factor.

Considering the lower bus width, AMD had to increase the efficiency in some way and they did this with color compression: the frame buffer color data is stored in a lossless compressed format. This reduces the amount of memory bandwidth required for frame buffer operations.

If we study the latest AMD slides, it seems that they are aiming on completely discontinuing the R9 280 and replacing it with the R9 285 which is cheaper to produce.

The Gigabyte R9 285 OC features an increased GPU frequency, from 918MHz to 973MHz, while the memory was left at default so it is running at 1375MHz.

The product is shipped inside a medium-sized cardboard enclosure, with the iconic logo and Gigabyte likes to remind us that we are dealing with a custom cooler solution and that this is an overclocked model:

On the back side of the box we will be able to spot some of the main product features:

After lifting the top cover we will be able to spot the card, which sits between several layers of cardboard and for extra protection it is also wrapped inside an anti-static bag:

If we do not have the necessary PSU connectivity options, Gigabyte has us covered, by including PCI-Express to Molex adapters; we are also offered one disk with drivers and also the Quick Installation Guide:

The Gigabyte R9 285 OC video card is fitted with the WindForce 2X with two ultra-PWM fans for increasing the cooling effectiveness; as it can be clearly seen, the cooling system exceeds the PCB width by a little bit: