Radeon HD 5850 review (CrossfireX)

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The Radeon HD 5850


The Radeon HD 5850

Last week we gave you a pretty deep insight on what the Radeon HD 5870 is all about. What you guys need to remember is that the Radeon HD 5850 is 100% similar to the feature set of that card. As such we'll be going a little less deep in this article, yet focus more on specifications, performance, layout and board design.

To understand the Radeon HD 5850 and 5870 we need to explain a thing or two though.

The new Radeon Series 5000 products are tagged under the family name 'Evergreen' and within that Evergreen family over the months to come we'll see several products released, what you see below is unconfirmed information, though:

  • Hemlock - dual-chip (X2) flagship graphics solutions powered by two RV870 chips (originally known as R800).
  • Cypress - single-chip high-performance graphics solution based on the RV870 chip that will replace the ATI Radeon HD 4890; this is the Radeon HD 5870 and as tested today the Radeon HD 5850.
  • Juniper - single-chip performance graphics solution that will replace the remaining Radeon HD 4870 and 4850 graphics boards. We expect Radeon HD 5750 and 5770.
  • Redwood - single-chip mainstream graphics solution(s) based on the RV830 chip that will replace both RV730 and RV740-based solutions.
  • Cedar - single-chip entry-level graphics solution(s) based on the RV810 chip.

The Radeon HD 5870 has gone on sale for $379, while the cheaper entry in the 5800 series, the Radeon HD 5850 is priced at $259. Both cards are fast, really fast. In the 5850's case it outperforms a GeForce GTX 285 in nearly any scenario as our tests will show.

So we have just established product positioning and price point, now let's have a peek at some of the key features for this product series:

  • 1GB GDDR5 memory
  • ATI Eyefinity technology with support for up to six displays (four on default reference cards)
  • ATI Stream technology
  • Designed for DirectCompute 5.0 and OpenCL
  • Accelerated Video Transcoding (AVT)
  • Compliant with DirectX 11 and earlier revisions
  • Supports OpenGL 3.1
  • ATI CrossFireX multi-GPU support for highly scalable performance
  • ATI Avivo HD video and display technology
  • Dynamic power management with ATI PowerPlay technology
  • DL-DVI, DL-DVI, DisplayPort, HDMI
  • PCI Express® 2.0 support

We'll address the preponderance of features in our article, but let's focus on the sheer technical specifications, transistor count for example.

The number of transistors on the 5850 is not at all different from the 5870. Both products have the same GPU, yet one cluster of shader processors simply has been disabled.

So while the Radeon HD 4870 had 956 million transistors embedded onto its die, the new Radeon HD 5800 GPUs have 2.15 billion transistors. Yes Sir, that is 2150 million transistors tucked away in a small chip. The fabrication node is 40nm for this product, resulting in a die size of 334 mm², which for AMD is monolithic, yet thanks to the 40nm fabrication process only (roughly) a third bigger than the previous 4890 GPU.

Now you'd think with so many transistors high clock frequencies would be an issue. Incorrect, the high-end Radeon HD 5850 will be clocked at a steady 725 MHz on its core and shader processor domain. The gDDR5 memory is clocked at 1000 MHz (4000 MHz effective). Both can be overclocked way higher though... more on that later, of course.

Shader processors then, we went from 800 Shader processors on the Radeon HD 4850/4870/4890 to 1440 shader processors (also called stream processors) on the Radeon HD 5850. The ROPs went up from 16 to 32 as well and sure... texture units from 40 to 72 as well.

  • Radeon HD 5850  has 9x 160 Shader clusters = 1440 Shader processors
  • Radeon HD 5870  has 10x 160 Shader clusters = 1600 Shader processors

But before you get blinded by all the specs in a few lines of text, let's break down the two new cards announced in comparison to last year's Radeon HD 4870.

  Radeon HD 4870 Radeon HD 5850 Radeon HD 5870
Process 55nm 40nm 40nm
Transistors 956M 2.15B 2.15B
Die Size 263 mm² 334 mm² 334 mm²
Core Clock 750 MHz 725 MHz 850 MHz
Shader Processors 800 1440 1600
Compute Performance 1.2 TFLOPs 2.09 TFLOPs 2.72 TFLOPs
Texture Units 40 72 80
Texture Fillrate 30.0 GTexels/s 52.2 GTexels/s 68.0 GTexels/s
ROPs 16 32 32
Pixel Fillrate 12.0 GPixels/s 23.2 GPixels/s 27.2 GPixels/s
Z/Stencil 48.0 GSamples/s 92.8 GSamples/s 108.8 GSamples/s
Memory Type GDDR5 GDDR5 GDDR5
Memory Clock 900 MHz 1000 MHz 1200 MHz
Memory Data Rate 3.6 Gbps 4.0 Gbps 4.8 Gbps
Memory Bandwidth 115.2 GB/s 128.0 GB/s 153.6GB/s
Maximum Board Power (TDP) 160W 151W 188W
Idle Board Power 90W 27W 27W

As you have been able to observe, the 5850 only has one shader processor partition less than the 5870. However its clock frequency is a good amount slower. But that's nothing we can't tweak out we dare to say.

One of the biggest accomplishments of the series 5000 graphics cards is the enhancement in the power design, the implementation of voltage and clock regulation is even more dynamic -- power management at a new level.

So we'll look purely at the Radeon HD 5850 now, in IDLE the GPU will clock down and lower its voltages on both GPU and memory. Have a look:

GPU Radeon HD 4870 Radeon HD 5850 Radeon HD 5870
Max. Board Power (TDP) 160W 151W 188W
Idle Board Power 90W 27W 27W

The card obviously achieves a low 27W IDLE power consumption by clocking down with several power states. Thus a low engine (core) clock frequency with lowered voltages and lower GDDR5 memory power. It's amazing though as your generic high-end graphics card would normally consume 50~60 Watts when it idles in Windows.

Things get even better though, the performance of the graphics card opposed to the last generation products has nearly doubled up in performance and design, yet the 5850 has a TDP (peak wattage) of only 151 Watts.

For architecture, PCB and voltage design we like to recommend you to read our reference Radeon HD 5870 review. But talk is cheap, let's have a look at the product.

Radeon HD 5850 CrossfireX

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