AMD R9 285 2GB CrossFire Scaling and Performance

Submitted by Jason Singh on Tue, 10/06/2015 - 12:20
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Introduction and Test System
1080p Crossfire Performance
1440p Crossfire Performance
Conclusion-Is it worth it?

We have two Sapphire R9 285’s, each spotting 2GB of DDR5 Memory with a 256 bus-width. This is intended as a follow up review to the A10-7870K where we tested crossfire performance but the quad core CPU proved to be quite a bottleneck, which is what lead us to test crossfire performance with the FX 8350. A CPU like the FX 8350, AMD’s highest line-up of CPUs, has more than enough of horse power to drive two R9 285’s. Even though the R9 285 has been replaced with the R9 380, it is still essentially the same GPU as the R9 380 has a slight bump in clock speeds and is currently being sold with 2GB and 4GB of DDR5 Memory. The R9 285 has been manufactured specifically for 1440p gaming.

Before we delve into the concept of crossfire we will be stating a few features of the R9 285 and why it is actually a unique GPU. The R9 285 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.

A single R9 285 can handle games at 1440p fairly well at high to medium settings. Running the R9 285 in crossfire does lead to a performance increase. "AMD CrossFire™ technology is the ultimate multi-GPU performance gaming platform. Unlocking game-dominating power, AMD CrossFire harnesses the power of two or more discrete graphics cards working in parallel to dramatically improve gaming performance. AMD CrossFire technology ready graphics cards fit practically every budget. With the flexibility to combine two, three or four GPUs, AMD CrossFire™ technology is the perfect solution for those who demand extreme performance. By combining the intelligent software algorithms of the AMD Catalyst suite with dedicated scaling logic in each AMD graphics processor, a gaming rig equipped with AMD CrossFire technology can deliver several times the performance of a system with a single graphics card. That’s performance you can count on to build your empire, take the pole position or keep your platoon alive." However, is that performance increase significant? Is it worth the added heat and power consumption? Is it value for money? We will be covering all these questions and answering them with benchmark charts and first hand user experience.

 

Test System

  • FX 8350 @4.8Ghz (Review)
  • Gigabyte 990FXA UD3 Rev 4.0
  • 16GB Kingston DDR3 Savage 2400Mhz Ram @1866Mhz CL 11 (Review)
  • Sapphire R9 285 2GB Crossfire
  • Noctua NH-D15S (Review)
  • Asus MG279Q 1440p Gaming Monitor (FreeSync Analysis)
  • 1TB Western Digital HDD
  • OCZ ZS 650 PSU
  • Windows 10
  • Drivers-AMD Catalyst 15.7.1 WHQL

 

Special Thanks to:

  • AMD for the FX 8350
  • AMD for the Gigabyte 990FXA UD3 Rev 4.0
  • AMD for the Sapphire R9 285 Dual X OC 2GB Crossfire
  • AMD for the Asus MG279Q Gaming Monitor
  • Kingston for the 16GB DDR3 Savage 2400Mhz Ram
  • Noctua for the NH-D15S

 

 

 

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