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AMD Radeon 6870/6850 Performance Preview November 05, 2010 Jacob Vandy VanDerWerf |
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Summary: Its been a little over a year since AMD ushered in the DX11 graphics era with the arrival of the Radeon 5870. Now AMD is refreshing their lineup with newer Radeon boards, beginning with the 6870 and 6850. Judging by their names you'd assume they'd be faster than the 5870, but that's not the case. The new Radeons are considerably cheaper though. Read on for the full details!
 Introduction | Page:: ( 1 / 15 ) |
It has been just over a year since AMD released the Radeon HD 5000 series, in which time they’ve shipped over 25 million of the first ever DirectX 11-capable graphics cards. NVIDIA took their sweet time in answering with their own GeForce GTX 400s last spring, which has since been adapted for various price points.
Now, a mere three months after the GTX 460 line of midrange video cards was launched to near universal acclaim, AMD has come back with their own new and improved midrange offerings. The Radeon HD 6850 and 6870 are poised to knock last generation’s most successful GeForce GPU from its perch, paving the way for the rest of the HD 6000 series in the coming months.
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Being meant to offer HD 5800-class performance at a lower cost and with less power consumption, the HD 6800 series represents AMD’s plain attempt to win back some of the market share at around the $200 price point, also known as the “gamer’s sweet spot.” By optimizing the HD 5800 architecture, they’re claiming they’ve achieved the best performance per watt possible and have produced the fastest sub-150W video card in the market today.
Perhaps more important than simply improving overall performance, AMD sought to put a larger emphasis on tessellation and geometry output than their first generation of DX11 cards. As you may have seen, performance in tessellation-heavy apps is something that the HD 5000 series sorely lacked in comparison to the GeForce 400s with their dedicated shading processors. That’s the kind of thing that can happen when you’re the pioneer of a generation, but AMD hopes to have rectified that oversight by improving such performance up to two-fold with the redesigned HD 6000 parts.
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The Radeon HD 6850 and 6870 will be replacing the HD 5850 and 5870 that have been on the market since October of 2009, at least until the 6900 series arrives. That’s an interesting proposition, to be sure, considering it’s a case of mid-range boards competing with much more expensive, high end ones. But hey, that’s why technology is so fun, right? To see if the 6800s succeed in filling those shoes and how they fare against the GTX 460, read on!
| Specifications | Page:: ( 2 / 15 ) |
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Representing the first of the Northern Islands family of GPUs, Barts Pro and Barts XT (6850 and 6870, respectively) were adapted from the Cypress chips used in the HD 5800 series. As a stop-gap measure to tide us over until the 28nm Southern Islands GPUs come out in 2011, AMD intended to offer comparable performance to last year’s models while lowering price and power consumption. Though they used the same 40nm process, the transistor count was cut down from over 2 billion in the 5800s to about 1.7 billion in these optimized chips and clock speeds were increased substantially:
| AMD Radeon HD 6800 Series Specs | ||
| HD 6850 | HD 6870 | |
| Process | 40nm | 40nm |
| Transistors | 1.7B | 1.7B |
| Core Clock | 775 MHz | 900 MHz |
| Stream Processors | 960 | 1120 |
| Compute performance | 1.5 TFLOPs | 2.0 TFLOPs |
| Texture Units | 48 | 56 |
| Texture Fillrate | 37.2 Gtexel/s | 50.4 GTexel/s |
| ROPs | 32 | 32 |
| Pixel Fillrate | 24.8 GPixel/s | 28.8 GPixel/s |
| Z/Stencil | 99.2 GSample/s | 115.2 GSample/s |
| Memory Size/Type | 1GB 256-bit GDDR5 | 1GB 256-bit GDDR5 |
| Memory Clock | 1,000 MHz | 1,050 MHz |
| Memory Data Rate | 4.0 Gbps | 4.2 Gbps |
| Memory Bandwidth | 128.0 GB/s | 134.4 GB/s |
| Idle Board Power | 19W | 19W |
| Max Board Power | 127W | 151W |
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Notes
Though basically cut from the same silicon, there are a few key differences that separate these two graphics cards. The increased core clock speed and stream processor count in the 6870 resulted in greater raw computing power than the 6850, for one. More texture units equates to a higher texture fillrate, etc. The only difference in memory is the 50 MHz between the two clocks, which separates them slightly by resulting bandwidth. There is also mild increase in maximum board power consumption, meaning the 6870 needs a second 6-pin power connector, as you’ll see on the next page.
Both appear to have significant advantages over the GTX 460, the most prominent being the much higher core clock speed and memory bandwidth. The latter is magnified in the case of the GTX 460 768MB, which has a narrower memory bus of 192-bit instead of 256-bit in the 1GB version and the Radeon 6800s. It is also worth noting that the 6800s are rated at lower TDPs than the 460s, at 127W and 151W compared to 150W and 160W.
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Officially, the HD 6850 and 6870 are priced at $179 and $239, and there are several SKUs available now at your favorite e-tailer. This puts them right around the prices the GTX 460s launched at in July, albeit with a wider gap between the two.
| Board Analysis | Page:: ( 3 / 15 ) |
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Radeon HD 6800 series reference design
At first glance, the 6850 and 6870 look almost identical. In fact, they have the same dual-slot cooling enclosure design, which is decidedly more rectangular than that seen on the HD 5000 series boards, but with a similar style of turbine fan. Oddly enough, the 6870 is almost entirely enclosed, while the 6850 has slots all along the side and rear of the cooler. Both setups do a sufficient job of keeping the GPUs cool, but it appears the 6850’s fan is less powerful than the one on the 6870, since it idles a good 10 degrees warmer:
| Sample Temperatures | ||
| Radeon HD 6800 Series | ||
| Idle Temp. | Load Temp. | |
| 6870 Stock | 30° C | 66° C |
| 6870 OC | 32° C | 68° C |
| 6850 Stock | 42° C | 70° C |
| 6850 OC | 42° C | 71° C |
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Upon closer inspection, you’ll find that there is a discrepancy in board length of about 3/4 of an inch. With the 6850 measuring in at exactly 9”, this means the 6870 is closer to 10”. Compared to the 5870 and 5850 (11” and 9.5”, respectively), that doesn’t sound so bad. However, the 6870 still dwarfs the GTX 460, which is just less than 8.5” long.
Both the board length and cooling method of the two speak volumes about each company’s design philosophy when it came to creating these midrange products -- Comparing the two graphics cards side by side, it quickly becomes apparent that the GTX 460 was crafted from the ground up for this application, while the 6870 was modified from the power-hungry, high end GPU of yesteryear.
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Another thing that’s changed since last year, sadly, is the removal of the ATI brand name. As can be plainly seen on the fan labels, the transition to “AMD Radeon Graphics” has officially been made. As an enthusiast, it’s easy to decry the decision to ditch the beloved moniker, but you can’t blame AMD for wanting to unify all of their products under a single name. This will become especially important when they come out with the CPU/GPU hybrid chip, Fusion, in the near future.
The 6870 has two 6-pin PCI-E power connectors on the side, while the 6850 has a single 6-pin connector on its end. Both have the same 5 display outputs: two DVI, one HDMI, and two mini DisplayPort connectors. Using a combination of these, a single graphics card can support up to 6 displays simultaneously using AMD Eyefinity. Of course, you can also have 2-way Crossfire, which we have included in our testing. Without further ado, turn the page and move on to the juicy bits!
| System Setup | Page:: ( 4 / 15 ) |
Intel Core i7-920 Bloomfield @ 3.6 GHz (Turbo Off)
EVGA X58 3-Way SLI
6 GB OCZ Gold Triple-Channel DDR3-1600 @ 1440 MHz
AMD Radeon HD 6870 1GB
AMD Radeon HD 6850 1GB
ATI Radeon HD 5870 1GB
ATI Radeon HD 5850 1GB
Catalyst 10.10
NVIDIA GeForce GTX 460 1GB
NVIDIA GeForce GTX 460 768MB
ForceWare 260.89
1TB Western Digital Caviar Black
Microsoft Windows 7 Ultimate 64-bit
Benchmarks
Unigine Heaven 2.1
Colin McRae DiRT 2
Aliens vs Predator
Metro 2033
STALKER: Call of Pripyat
Just Cause 2
Battlefield: Bad Company 2
Far Cry 2
Crysis: Warhead
| Unigine Heaven 2.1 – DirectX 11 | Page:: ( 5 / 15 ) |
Notes
High shaders, Normal tessellation
| DiRT 2 – DirectX 11 | Page:: ( 6 / 15 ) |
| Aliens vs Predator – DirectX 11 | Page:: ( 7 / 15 ) |
| Metro 2033 – DirectX 11 | Page:: ( 8 / 15 ) |
Notes
Advanced PhysX Off
| STALKER: Call of Pripyat – DirectX 11 | Page:: ( 9 / 15 ) |
| Just Cause 2 – DirectX 10 | Page:: ( 10 / 15 ) |
Notes
Bokeh filter Off, GPU-simulated water Off
| Battlefield: Bad Company 2 – DirectX 11 | Page:: ( 11 / 15 ) |
| Far Cry 2 – DirectX 10 | Page:: ( 12 / 15 ) |
| Crysis: Warhead – DirectX 10 | Page:: ( 13 / 15 ) |
Notes
It looks like there’s a CPU bottleneck here, with the dual-6800 configurations maxing out at around 60 FPS, regardless of resolution.
| Power and overclocking | Page:: ( 14 / 15 ) |
Power Consumption
Overclocked Performance
| Conclusion | Page:: ( 15 / 15 ) |
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Though not as exciting as the HD 5000 series, this refresh of the Radeon line does well to update performance enough to remain competitive with what NVIDIA has done with their mainstream Fermi products. It makes sense that AMD would come out with new mid-range cards first, instead of high-end ones as they traditionally do; the GTX 460 was such a success that they must have felt the need to come up with a better alternative as soon as possible. However, we must detest the redefinition of the Radeon nomenclature… x800 series graphics cards have traditionally been high-end products, which may lead to confusion with some consumers.
As it turns out, the HD 6870 was indeed faster than the GTX 460 1GB in every test we conducted, with performance improvements of anywhere from 8% to 21%. All the while, its power consumption and temperatures remained on par with the much smaller GeForce board. As for the HD 6850, it fits snugly in between the 768MB and 1GB versions of the GTX 460 overall, though in a few cases it matched or slightly exceeded the latter. In response to this, NVIDIA has cut prices on both GTX 460 boards as well as the GTX 470, which they would like to be able to compete more closely with AMD’s new offering:
| Mid-range GPU Pricing | |||||
| GeForce and Radeon | |||||
| GTX 460 768MB | HD 6850 | GTX 460 1GB | HD 6870 | GTX 470 | |
| SEP (suggested e-tail price) | $169.99 | $179.99 | $199.99 | $239.99 | $259.99 |
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Of course, you will find SKUs of each GPU at prices above or below what you see here, hence why they’re referred to as suggestions. Whether a specific graphics card is factory overclocked or has a mail-in rebate or other things like that will be major determiners in pricing variations. Still, sorting them in this way actually translates pretty well to their ranking in performance, which is surely not a coincidence. That’s great for anyone looking to buy a new video card in this price range, since you can get a little more or a little less performance depending on exactly how much you’ve got to spend.
We found that AMD used the term “comparable” rather loosely when referring to the 6800 series’ performance in relation to the 5850 and 5870. Just as the GTX 460 was beaten by a comfortable margin, the 5870 had no problem outpacing the 6870. The 5850 is a much closer competitor, though ultimately falls behind due to its lower core clock speed. We would venture to guess that the prices of the 5850 and 5870 will drop to compensate for these new releases before they sell out completely; the 5850 (currently ~$250-300) shouldn’t cost more than the 6870, and the 5870 certainly isn’t worth nearly $400 anymore.
In terms of overclocking potential, the HD 6800 series doesn’t hold a candle to the GTX 460s. Since AMD had to crank up the clock speeds in order to boost performance with fewer transistors, there isn’t a whole lot left for the end user to squeeze out. We were only able to gain an extra 50 MHz on either core, and for the 6850 that seems to be a hardcoded limitation… Apparently AMD didn’t want people buying the cheaper card and overclocking it to 6870 speeds. As such, the performance increase in both cases was less than 10%, compared to upwards of 25% with overclocking the GTX 460. If you wanted, you could actually have performance comparable to the HD 6870 for $40 less by getting a GTX 460 1GB and overclocking it. To illustrate, here is the kind of results you can expect from a factory overclocked board such as the EVGA GeForce GTX 460 1GB FTW Edition:
| GTX 460 1GB Performance | ||
| Overclocked to 850/1000 | ||
| GTX 460 | HD 6870 | |
| Crysis: Warhead | 39.8 FPS | 40.5 FPS |
| Metro 2033 | 45 FPS | 44.3 FPS |
| STALKER: CoP | 34.1 FPS | 31.1 FPS |
| Aliens vs Predator | 27.8 FPS | 27.1 FPS |
| Unigine Heaven | 30.2 FPS | 26.7 FPS |
| Far Cry 2 | 81.8 FPS | 70 FPS |
| Just Cause 2 | 63 FPS | 61.1 FPS |
| DiRT 2 | 81.3 FPS | 72.8 FPS |
| BF: Bad Company 2 | 62.5 FPS | 61.6 FPS |
| 1920x1200 resolution | ||
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However, whether they’re keen on overclocking or not, AMD fans are surely happy to hear that the Red team is back in the game. November is shaping up to be another interesting month for video cards, with high-end offerings from the GeForce 500 series and Radeon HD 6900 series set to make their respective debuts. Rest assured, you can count on your friends here at FiringSquad for coverage, so y’all come back now, ya hear?