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Sapphire Radeon HD6850 and HD6870 Review

The new 6800 series has seen hardware architecture changes, with a focus on strengthening tessellation and geometry throughput. Avid readers of KitGuru will have seen over recent months that nVidia Fermi hardware has been leading the way in titles such as UniGine Heaven Benchmark, a synthetic test which relies heavily on Tessellation performance.

The 6800 series has a reconfigured core design which offers up to 2.0 TeraFLOPS and 24 Gigapixels per second performance. The command processor is linked to the graphics engine as seen in the diagram above, with the new generation 7 Tessellator. The Dual rasterizers and 12-14 SIMD engines tied to a 256 bit GDDR5 memory interface help to improve performance beyond the levels of the last generation, while using 25% less silicon.

AMD HD5850
AMD HD6870
Die Size
334 mm2
2.15 billion
1.7 billion
Memory Bandwidth
134.4 GB/sec
Geometry Throughput
725 million polygons/sec
900 million polygons/sec
SIMD Engines
Stream Processors
Texture Units
Z/Stencil ROPs
Colour ROPs
Max Board Power
Idle Power

The table above shows a direct comparison against the HD5850 and HD6870. The HD6870 has less texture units, SIMD engines, Stream Processors with a lower memory bandwidth but the Geometry throughput has been significantly increases from 725 million polygons per second to 900 million polygons per second. The new design is more efficient and with the die shrink requires less power at idle.

Hardware Tessellator Progression
Generation 1
ATI Radeon 8500
Fixed Function PN Triangles (TRUFORM)
Generation 2
Microsoft Xbox 360
Displacement mapping, adaptive tessellation
Generation 3
AMD Radeon HD2000 family
Dirext X 10 compatibility
Generation 4
AMD Radeon HD 3000 family
Direct X 10.1 compatibility
Generation 5
AMD Radeon HD 4000 family
Performance Enhancements
Generation 6
AMD Radeon HD 5000 family
Direct X 11 compatibility
Generation 7
AMD Radeon HD 6800 Series
Improved Thread Management and buffering

The updated Tessellation unit, called ‘Generation 7’ brings new thread management capabilities as well as buffering enhancements to the table. This means that performance is increased by up to two times when directly compared to the HD5000 series. This should mean that AMD are closely competitive with similarly priced nVidia Fermi hardware, we will look at performance later in this article. AMD’s internal testing shows that the HD6870 achieves twice the tessellation performance of the HD5870.

Tessellation is a hotly discussed topic right now, and it is a bone of contention between nVidia and AMD. Our recent interview with Richard Huddy opened a few eyes, as he said “nVidia is pushing a single message and that’s tessellation. Tessellation is about enriching detail, and that’s a good thing, but nVidia is pushing to get as much tessellation as possible into everything. With artificial tests like Stone Giant, which was paid for by nVidia, tessellation can be done down to the single pixel level. Even though that pixel can’t be broken away from the 3 other pixels in its quad. Doing additional processing for each pixel in a group of 4 and then throwing 75% of that work away is just sad.”

AMD’s stance on this is “Tessellating the Right Way” – which means a focus on the most efficient tessellation usage models with 16 pixels per polygon combining solid image quality with high levels of performance. Adaptive Tessellation is how they want to approach it, using high levels for objects close to the front of the screen (and in eye shot of the gamers) and then switch to lower levels for distant and simple objects to help improve performance while avoiding geometry aliasing problems.

The image above was captured from Alien V Predator and showcases the new Morphological Anti-Aliasing technique from AMD which is a post process filtering technique accelerated with DirectCompute. It delivers full scene anti Aliasing and it is not limited to polygon edges or alpha tested surfaces. The system is faster than super sampling with similar performance levels to edge detect CFAA, but it applies to all edges. This can be enabled from Catalyst Control Center and is compatible with any Direct X 9/10/11 supported application.

Anistrophic Filtering has also been fine tuned and enhanced with a newly refined algorithm in place. It addresses visible discontinuities in very noisy textures offering smoother transitions between filter levels. It also maintains full performance and angle independence.

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  • JC

    Your 6850 have 1120 sharders. o_o”

  • harry

    these are really good cards, love the performance and price.

  • Hank

    Excellent boards those, really look the part and performance is awesome. overclocking is great !

  • P1n3apqlExpr3ss

    Shit… haha 6850 is a killer card and guess what? its right in the price range im looking at 😀
    Only thing i can say reading other reviews is that the 6850 reference cooler is pretty weak. These sapphire cards look great for the money 😀 (6850) will reserve judgement til i seem overclocked 6870s

  • Tri Color

    Killer card indeed, couldnt agree more.

  • Terrid Fayid

    HD6870 is good, but I dont like reference designs, too noisy/hot/ I will wait for sapphires or XFXs custom cooling one.

  • Harris

    HD6870 is the one I would get, but not reference version. will wait a month for vapor X or toxic version.

  • Trev

    6870 reference design is a waste, waiting on other solutions

  • steve

    the hd6870 isn’t my first choice until they get third party products out of the stable,

    Its always the way with launches, but its weird AMD have let their partners make third party solutions for 6850s

  • Jon

    over clocked HD6870s might be hard to get out the door with such poor over clocks on the core. seems both boards max out around 950

  • Frank

    While these cards aren’t awe inspiring, when you look at the price 150 for a 6850. about the same as the 5770. 25% more performance, looks good.

  • Lux

    those overclocks on the 50 are great. id say overclocked versions will be out really soon. vapor x anyone ?

  • Michael

    As JC stated, this 6850 has 1120 shaders instead of the default 960…

  • Tech head

    The bottom gpuz screenshot is for the 6870

  • Ned

    I get the same 3dmark vantage score as this HD6850. I was hoping I might even up with a 1120 shader version but sadly not 🙁

  • @ Jon

    I saw in another review that they managed to get the Sapphire 6870’s core clock to 1000mHz stable. I’m sure if put under water, these cards will have a bit more overclocking headroom anyway.

  • Efe Eren Kaya