Sapphire R9 285 Dual-X OC 2GB
The R9 285 is commonly viewed as a rebrand of the R9 280. While many are of this opinion, after testing it, we can confirm with certainty that it is somewhat different. AMD has brought about a lot of new features with the introduction of the Tonga GPU, the R9 285 2GB. It supports True Audio which was initially only supported by the R9 290 and R9 290X. This may come as a surprise to some as it does not require a Crossfire connector. It supports a superior solution to Crossfire, XDMA. At a principle level, XDMA dispenses with the external bridge by opening a direct channel of communication between the multiple GPUs in a system. This channel operates over the very same PCI Express® bus in which your AMD Radeon graphics cards are currently installed. The exclusive function of that bus is to shuttle graphics data between GPUs and your processor, so it’s already well suited to the new task of collecting and showing the data each GPU is working on when playing games. AMD claims that the R9 285 has increased tessellation performance over the previous generation GPU’s. The R9 285 has support for 16-bit floating point and integer values. This proves to be beneficial in low power settings where 16-bit precession seems to do the job. AMD has conventionally used 32-bit values and have shifted to 16-bit with the Tonga GPU which would result in saving not only power but also internal bandwidth without a corresponding degradation in terms of image quality. Colour Compression has been another new addition to the Tonga architecture. Frame buffer data is now stored in a lossless compressed manner and the GPU can now read and write compressed data. This will ultimately lead to tremendous bandwidth efficiency gains and would possibly justify AMD's decision to shrink the Bus Width to 256 unlike the R9 280 and R9 280X which both have a 384 Bus Width. Finally, the R9 285 comes with a new video decoder block for full hardware decode of H.264 4K streams. This would mean that the new block would be able to handle decoding 4096x2304 streams at 60fps.
Features and Specifications
|GPU||1792 Stream Processors
Graphics Core Next (GCN)
965 MHz Engine Clock
|Memory||256 bit Memory Bus
GDDR5 Memory Type
2048 MB Size
|Displays||Maximum 4 Outputs|
|Output||1 x DVI-I
1 x DVI-D
1 x HDMI
1 x DisplayPort
|Resolution||4096x2160 Pixel DisplayPort Resolution
4096x3112 HDMI Resolution
Shader Model 5.0
AMD ZeroCore Power Technology
AMD HD3D Technology
AMD Tress FX technology
AMD TrueAudio technology
Universal Video Decoder (UVD)
|Form Factor||2 Part Slot Occupied
264(L)X113(W)X34(H) Dimension /mm
|System Requirement||500 Watt Power Supply (Suggestion)
2 x 6-pin AUX Power Connector
CD-ROM or DVD-ROM drive for installing software
PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard.
The R9 285 which we received from AMD was the Sapphire R9 285 Dual-X 2GB OC. While the reference R9 285 is set to run at a clock frequency of 918/1375Mhz, the Sapphire R9 285 has been factory overclocked to 965/1400Mhz. For the purpose of this review we have considered the Factory overclock as stock clocks. The packaging of the GPU was good as the GPU was securely held in place and was padded well enough to prevent any damage. The pictures below will give one a better idea of the Sapphire R9 285 Dual-X 2GB OC.
The accessories received in the box consisted of the GPU Quick Installation Guide, Sapphire Warranty Information, driver and utility CD, two 6 pin converters, and a shiny Sapphire sticker.
Here is the first glimpse of the GPU with it's protective cover still stuck on to it.
As we remove that protective cover we notice the shiny, plastic shroud of the cooler. The cooler in itself is quite large and extends a little over the length of the PCB.
This is the button which enables UEFI mode.
Here's a glimpse of the PCB of the GPU. It's a blue PCB for those wondering about the colour scheme matching with that inside the case.
Coming to the memory modules of the GPU. We see that Sapphire has chosen to go with Elpida Memory. In terms of overclocking Samsung Memory wears the crown, followed by Hynix Memory chips which seems to do quite well and lastly we have Elpida Memory. The Elpida Memory that has been used is rated for 1500Mhz but has been set to 1400Mhz by Sapphire. So when it comes to overclocking the memory, we may be looking at a maximum of 1500Mhz or maybe 20Mhz over that. GPU vendors sometimes are forced to use Elpida Memory due to the lack of availability of Samsung and Hynix Memory. Most, if not all other R9 285's make use of Elpida Memory. For those who are commonly using their GPU's for folding will know the benefit of having Hynix Memory modules. AMD's refresh of the R9 285, the R9 380 comes with Hynix Memory.
The VRMs of the GPU have a heatsink over them. This will prevent them from overheating. Overheating VRMs could have disastrous effects. Not only does it lead to GPU clocks throttling but can also lead to permanent damage of the GPU.
The picture above shows the 2x6 pin connectors which the GPU utilizes. If one looks closely, one would notice the other two solder points next to the 6 pin connector, indicating that it could have been a 8+6 powered GPU, thus, drawing more power and would ultimately lead to more overclocking headroom. However, as AMD has tried to reduce power consumption with the Tonga GPU, we are sure that they would prefer the vendors sticking to the 2x6 pin power draw.
This is a closer look at the application of thermal paste by Sapphire. We also notice the Thermal pads stuck the heatsink. These are for the memory chips on the card. They are essentially cooled by these thermal pads. On further inspection we did notice that the heatsink used is in fact the Vapor-X chamber cooler and not the conventional Dual-X cooler found on the Sapphire R9 270, 270X.
Here is a closer look at the core of the Tonga GPU. We removed the pre-applied thermal paste and decided to use our own.
We used the Noctua NT-H1 Thermal Compound and can confirm a slight decrease in load temperature which are always welcome.
Overclocking and Undervolting
Overclocking the R9 285 was fairly easy. We used MSI Afterburner but one could give Sapphire TriXX a go as it’s a pretty small and useful overclocking software. The voltage in MSI Afterburner could be increased by +100mv whereas the threshold in Sapphire TriXX was higher as it gave the option of increasing the voltage all the way to +200mv. For the purpose of this review we left the voltage at stock, 1.15v as we wanted to give our viewers a good idea of what most users could achieve with the R9 285. The R9 285 managed to maintain stability at 1100/1500Mhz making this a very good overclock on stock voltages. In order to stop all thermal throttling we increased the Power Limit in MSI Afterburner to +20 and managed to maintain constant in game clock speeds of 1100/1500Mhz. For those users who are happy enough with the stock performance of the GPU may look towards undervolting which will not reduce the performance of the GPU as stock clocks would still be maintained in games. Much to our surprise we were able to undervolt the R9 285 by -70mv in MSI Afterburner, reducing the voltage from 1.15v to 1.08v. This seems to be a good way of reducing overall power consumption, especially when running in Crossfire Mode.