by Sergey Lepilov
08/02/2011 | 12:03 PM
Perhaps the main reason why AMD and Nvidia develop dual-processor graphics cards is that they want to emphasize their superiority over the competitor, so such products are, as a rule, based on expensive top-end GPUs. Clock rates and even functional subunits may be sacrificed in order to keep the power consumption and heat dissipation of a dual-processor graphics card within reasonable limits, yet formally AMD Radeon HD 6990 and Nvidia GeForce GTX 590 are indeed based on the fastest GPUs available.
Well, most rules have exceptions. PowerColor, a subsidiary of TUL Corporation, has taken on the risk of developing a dual-processor graphics card with midrange rather than top-end GPUs. The product is called PowerColor Radeon HD 6870X2.
You will learn how fast, hot and noisy the new graphics card is from this review.
The card comes in a big and pretty-looking box with steel-like symbols “X2” on its front. From the text on the box you can learn the name of the product, the amount of graphics memory, what video outputs it has and what multi-monitor configurations it supports. A sticker informs you that the game DiRT 3 is shipped with the product.
The back of the box offers more information like descriptions of the product’s key features, cooling system and “platinum” PCB. There is even a diagram comparing the performance of PowerColor’s dual-chip card with that of the Nvidia GeForce GTX 580.
Besides a DiRT 3 coupon, the accessories include two power adapters, one mini-HDMI->HDMI adapter, one DVI-I->VGA adapter, a CrossFire connector, a CD with drivers and an installation guide.
The graphics card is manufactured in China. The warranty period is 2 years. Its recommended price is $499 but it sells in retail for more ($509 and higher), just as you can expect from a new and unique product.
PowerColor’s product is big. It is a mere 1 millimeter shorter than the longest reference card, the 305-millimeter Radeon HD 6990. Well, its PCB is actually only 294 millimeters long while the rest of its length is due to the cooler’s plastic casing.
The Radeon HD 6870X2 isn’t extraordinary in terms of its other dimensions (38 x 111 millimeters) if you don’t count in the thick copper heat pipes sticking out of the cooler’s heatsink. Take note that some of the memory chips are installed on the reverse side of the PCB.
The graphics card has two dual-link DVI connectors, one HDMI, and a couple of mini-DisplayPorts (version 1.2).
There are plastic caps on the card’s connectors to protect them against dust. The rest of the mounting bracket is a vent grid for exhausting the hot air out of the system case.
You can find one CrossFireX connector and two 8-pin power connectors on the PCB.
As we know, the reference AMD Radeon HD 6870 has a peak power draw of 151 watts, so the dual-chip card is going to require more than 300 watts. PowerColor recommends a 600W or higher PSU for a computer with a Radeon HD 6870X2.
The cooling system is fastened with screws around the GPUs. We undid the screws to have a closer look at the PCB.
The two Barts XT chips are turned around by 45 degrees. Each is surrounded by four memory chips (four more are on the reverse side of the PCB). You can also see a switch chip in between the GPUs. The card is fitted with a 13-phase power system and features high-quality components (the so-called Platinum Power Kit). The ferrite chokes and the Texas Instruments 59901M DrMOS packs (driver and MOSFET combos) are expected to ensure stable operation of the graphics card throughout the entire service life.
The power system is managed by two CHiL Semiconductor CHL8214 controllers.
The two identical Barts XT chips were manufactured on 40nm tech process in Taiwan on the 46th week of 2010.
Each chip has 1120 unified shader processors, 56 texture-mapping units and 32 raster operators. In 3D applications they are clocked at 900 MHz and have a voltage of 1.172 volts. In other words, this card uses the same GPUs as you can find on the majority of ordinary Radeon HD 6870s. In the power-saving mode the GPU clock rate is dropped to 100 MHz and the voltage to 0.95 volts.
The Lucid HydraLogix 200 (LT22102) chip you can see between the GPUs is revision A1 and supports up to 48 PCI Express 2.0 lanes. Besides linking the GPUs in CrossFireX mode, it allows you use the dual-processor card together with Nvidia-based products (you’ll need to install the HydraLogic driver for that).
As opposed to most AMD-based graphics cards that use Samsung or Hynix memory chips, the PowerColor Radeon HD 6870X2 comes with GDDR5 memory from Elpida. The chips are marked as W1032BABG-50-F.
Their rated access time is 5.0 nanoseconds, which means a clock rate of 5000 MHz. The card’s actual memory clock rate is 4200 MHz, the same as with the reference Radeon HD 6870. There is a total of 2048 megabytes of graphics memory on board but each GPU can only access 1024 megabytes. The memory bus is 256 bits wide.
GPU-Z doesn’t make it clear that we’re dealing with something other than an ordinary Radeon HD 6870.
The line “ATI CrossFire = Enabled (2 GPUs)” provides a hint, but you can just as well suppose that there are two separate Radeon HD 6870 cards installed in the system. :)
You can learn the key features of the cooling system deployed on the PowerColor Radeon HD 6870X2 from the text on the back of the product box.
We were surprised to find that the direct-touch technology of this cooler is going to be 50 times as efficient as a conventional copper base although the diagram suggests a much smaller difference. PowerColor’s marketing people seem to have run dry of fresh promotion ideas.
Anyway, the cooler is quite an interesting thing.
It consists of two separate aluminum heatsinks each of which has three copper heat pipes, 8 millimeters in diameter.
The slim (0.25 mm) and narrow (10 mm) fins are press-fitted onto the pipes. There are 2mm gaps between the pipes in the cooler’s base which may lead to local overheat of one or another of the GPU subunits. We guess it would be better to have four 6mm pipes right next to each other. Is this technology yet to reach GPU coolers?
The heatsinks are cooled with two fans fitted into a plastic casing:
Oddly enough, the fans are different. The 9-blade one has a diameter of 85 millimeters and a 33mm motor. It is closer to the card's video outputs. The other fan is 75 millimeters and has 11 blades. Its motor is 29 millimeters in diameter.
The fans are both manufactured by Everflow and run on sleeve bearings. Their speed is regulated automatically.
Now let’s see how efficient and noisy this cooler is and how well it copes with its rather daunting task. To accomplish this, we used the Aliens vs. Predator (2010) test. We ran it five times with maximum graphics quality settings in 1920x1080 resolution and 16x anisotropic filtering. Besides, we also fried the card up with the FurMark 1.9.2 stability test at 1920x1080. We used MSI Afterburner 2.2.0 Beta 5 and GPU-Z 0.5.4 to monitor the graphics card’s temperatures, frequencies and fan speed. All the tests were carried out with a closed system case at an ambient temperature of 28-29°C.
First let’s check out the temperature of the card when running the 3D game, the fans being controlled automatically (left) or working at their full speed (right):
Despite the high ambient temperature, the GPUs were only as hot as 84-85°C in the automatic fan regulation mode and 77-79°C hot at the maximum speed of the fans. We'd say this is a very good result for a dual-processor graphics card. We can also note that the two GPUs are about the same temperature whereas the GPUs of a Radeon HD 6990, for example, differ in temperature by 10-12°C due to the sequential cooling system design. It’s a shame that the cooler of the PowerColor Radeon HD 6870X2 is obviously not perfect. The card might be cooled even more effectively with less noise.
The graphics card was expectedly hotter when running FurMark:
The GPUs were an alarming 94-95°C hot, the test proving to be an ordeal for the graphics card considering the hot weather. We wouldn’t risk such a test again.
We also measured the level of noise using an electronic noise-level meter CENTER-321 in a closed room about 20 sq. meters large. The noise-level meter was set on a tripod at a distance of 15 centimeters from the graphics card which was installed on an open testbed. The mainboard with the graphics card was placed at an edge of a desk on a foam-rubber tray.
The bottom limit of our noise-level meter is 29.8 dBA whereas the subjectively comfortable (not low, but comfortable) level of noise when measured from that distance is about 36 dBA. The speed of the graphics card’s fans was being adjusted by means of a controller that changed the supply voltage in steps of 0.5 V.
For the comparison’s sake, we’ve added the results of the reference AMD Radeon HD 6870 and Nvidia GeForce GTX 580 into the next diagram (the dotted lines mark the top speed of the fans when regulated automatically in the gaming mode):
Thus, the reference Radeon HD 6870 is the noisiest card of the three, even though its radial fan reached a higher speed than the fans of the other cards. The PowerColor Radeon HD 6870X2 and the GeForce GTX 580 are rather close in terms of noisiness, the two fans of the dual-processor card rotating at a lower speed than the radial fan of the GTX 580. Subjectively, PowerColor's cooler seems to be softer and somewhat more agreeable to the ear than the reference GTX 580 cooler, yet neither is truly comfortable in 3D mode. These cards are not really quiet even in 2D mode, though.
We wouldn't have expected any overclocking records even from a regular graphics card, let alone a dual-GPU one, under the hot weather we had during our tests. Anyway, we managed to speed our Radeon HD 6870X2 up a little without losing in stability and image quality.
The GPUs worked at a clock rate of 940 MHz. The graphics memory frequency was set at 4840 MHz. The temperature of the card didn’t change much at that:
The peak temperature of the GPUs was 86-89°C and the fans were but slightly faster compared to the same test at the card’s default clock rates.
All graphics cards were benchmarked in a closed system case with the following configuration:
Here are the graphics cards that we will use for performance comparison purposes:
We also included the reference AMD Radeon HD 6870 in order to evaluate the efficiency of the dual-GPU PowerColor with the same graphics processor working at the same frequency. GeForce GTX 580, in its turn, is included into this test session as a direct competitor to Radeon HD 6870X2 in terms of price. Even PowerColor compare their graphics cards specifically against GeForce GTX 580 and stress the advantages of their solution over the rival:
And the two GeForce GTX 560 graphics cards tested in an SLI configuration have recently been reviewed individually in our article called GeForce GTX 560 from EVGA, Gigabyte and MSI.
In order to lower the dependence of the graphics cards performance on the overall platform speed, I overclocked our 32 nm six-core CPU with the multiplier set at 25x and “Load-Line Calibration” (Level 2) enabled to 4.5GHz. The processor Vcore was increased to 1.46875V in the mainboard BIOS:
The 6 GB of system DDR3 memory worked at 1.5 GHz frequency with 7-7-7-16_1T timings and 1.64V voltage. Turbo Boost and Hyper-Threading technologies were disabled during our test session.
The test session started on July 24, 2011. All tests were performed in Microsoft Windows 7 Ultimate x64 SP1 with all critical updates as of that date and the following drivers:
The graphics cards were tested only in one today’s most popular resolution: 1920x1080. The tests were performed in two image quality modes: “Quality+AF16x” – default texturing quality with enabled 16x anisotropic filtering and “Quality+ AF16x+AA4(8)x” with enabled 16x anisotropic filtering and full screen 4x anti-aliasing (MSAA) or 8x if the average framerate was high enough for comfortable gaming experience. We enabled anisotropic filtering and full-screen anti-aliasing from the game settings or configuration files. If the corresponding options were missing, we changed these settings in the Control Panels of Catalyst and GeForce/ION drivers. There were no other changes in the driver settings.
The list of games and applications used in this test session is identical to what we used in our previous article. It includes one popular semi-synthetic benchmarking suite, one technical demo and 12 games of various genres:
If the game allowed recording the minimal fps readings, they were also added to the charts. We ran each game test or benchmark twice and took the best result for the diagrams, but only if the difference between them didn’t exceed 1%. If it did exceed 1%, we ran the tests at least one more time to achieve repeatability of results.
PowerColor’s dual-processor product comes out the winner of our first test. It enjoys an advantage of 23 to 32% over the GeForce GTX 580, depending on the graphics quality mode. It is also 95% ahead of the regular Radeon HD 6870, which proves the high efficiency of CrossFireX technology in 3DMark 2011. We should also note the strong performance of the SLI tandem built out of the two inexpensive GeForce GTX 560s. They take second place.
The PowerColor Radeon HD 6870X2 is even more impressively faster than the GeForce GTX 580 in this beautiful benchmark. The gap varies from 28 to 48%. The new dual-processor card is also twice as fast as the ordinary Radeon HD 6870. The two GeForce GTX 560s perform well in SLI mode, too. Considering that they are going to cost you $350-370 but beat the $500 GeForce GTX 580, that SLI configuration looks quite attractive.
The PowerColor card beats the GeForce GTX 580 in BattleForge: Lost Souls, too. The gap varies from 13 to 35%, depending on the graphics quality mode. The Radeon HD 6870X2 looks good compared to the single-processor Radeon HD 6870 and adds 93-95% to the latter's speed. Take note that the efficiency of Nvidia's SLI technology is close to 100% here, so the SLI configuration beats the PowerColor card in the FSAA mode.
The Radeon HD 6870X2 is again ahead of the GeForce GTX 580 but the gap is smaller than in the three previous tests. CrossFireX technology is less efficient here than before, so the SLI configuration built out of two GeForce GTX 560s takes the lead. We seem to have assembled one very fast SLI tandem here.
The Radeon HD 6870X2 might be praised for competing with the more expensive GeForce GTX 580 in Metro 2033: The Last Refuge if it didn't have such a low bottom speed. The two SLI-linked GeForce GTX 560s do not have such a problem and have a higher bottom speed compared to the single GTX 560.
Running a little ahead, we can tell you that it’s in Just Cause 2 that the dual-processor Radeon HD 6870X2 enjoys the biggest advantage over the GeForce GTX 580: 83% without full-screen antialiasing and 74% with 4x MSAA. The GeForce GTX 560 SLI configuration isn’t competitive, but the results of the single Radeon HD 6870 indicate that the game engine favors AMD-based products.
This is the sixth out of the seven tests we’ve seen so far in which the dual-processor Barts XT-based card is faster than the single-processor GF110-based one. CrossFireX technology works perfectly here, doubling the average frame rate.
Lost Planet 2 prefers Nvidia-based products. Comparing the single Radeon HD 6870 with the PowerColor Radeon HD 6870X2, we can see that CrossFireX is only 67-73% efficient in this game, the second worst result in this test session.
Here is the worst test for CrossFireX. AMD-based graphics cards still have problems with full-screen antialiasing in this game hence the low performance. With FSAA turned off, the PowerColor Radeon HD 6870X2 is quite competitive to the GeForce GTX 580.
The PowerColor card is good in this game, beating the GeForce GTX 580 as well as the GeForce GTX 560 SLI configuration. It is also almost 100% faster than the single Radeon HD 6870.
Despite the game’s predilection towards Nvidia GPUs, the PowerColor Radeon HD 6870X2 beats the GeForce GTX 580 even here. The test is won by the GeForce GTX 560 SLI configuration, though.
The Radeon HD 6870X2 is faster than the GeForce GTX 580 in Crysis 2 which has recently acquired DirectX 11 support. Like in Metro 2033: The Last Refuge, we see that both multi-GPU configurations have problems with their bottom speed which is lower than with the respective single-GPU graphics cards.
The PowerColor HD 6870X2 meets no problems and no competition in this test.
This game produces the same results as the previous test.
Here is a table with the detailed test results for your reference:
Let's now examine summary diagrams.
The diagrams show average frame rates only. The first one indicates how fast the dual-processor Radeon HD 6870X2 is in comparison with an ordinary Radeon HD 6870.
The dual-processor card is up to 100% faster than its single-processor cousin across most tests. The gap is small in but a few games: StarCraft II: Wings of Liberty, Lost Planet 2 and the FSAA-less modes of S.T.A.L.K.E.R.: Call of Pripyat and Metro 2033: The Last Refuge.
The next diagram compares two similarly priced products, PowerColor Radeon HD 6870X2 and GeForce GTX 580, the latter’s performance being the baseline.
Save for Lost Planet 2 and the FSAA mode of StarCraft II: Wings of Liberty, the PowerColor is faster than its rival, enjoying a very large advantage in such games as Just Cause 2, Aliens vs. Predator (2010), Total War: Shogun 2 and Sid Meier's Civilization V. The average advantage across all the tests is 25%.
Here are a few more diagrams that might be interesting to you. The next one compares the PowerColor Radeon HD 6870X2 with the SLI configuration built out of two GeForce GTX 560s:
And this is a comparison of the single Radeon HD 6870 (900/4200 MHz) with the single GeForce GTX 560 (870/4080 MHz):
Here is the GeForce GTX 560 SLI configuration compared to the GeForce GTX 580:
There’s no need to comment on these results except that two GeForce GTX 560s are going to cost you some 20% less than one GeForce GTX 560.
The PowerColor Radeon HD 6870X2 is a unique product that delivers high performance. Despite some minor problems with the minimal speed, the dual-processor card from PowerColor left no chance to the Nvidia GeForce GTX 580 in our tests. Most importantly, the PowerColor Radeon HD 6870X2 costs as much as reference GeForce GTX 580s and is expected to get even cheaper eventually. The card's cooling system, even though not perfect, copes with its job with less noise than the GTX 580's reference cooler. Besides, the Lucid HydraLogix chip allows combining the PowerColor card with any Nvidia-based product into a single subsystem to get even higher performance. Added to that are awesome accessories, nice-looking packaging and a 2-year warranty.
We can note that two reference AMD Radeon HD 6870s are going to cost you no more than $360 today, yet they would require a mainboard with two fully-functional PCI Express x16 slots (which are unavailable on the popular LGA1155 platform). They would need more power cables and would produce more noise. So, the PowerColor Radeon HD 6870X2 is quite a competitive product and we are now waiting for Nvidia's response like a dual-chip GeForce GTX 560 Ti “X2” priced at about $400 and equipped with a low-noise cooler. It might be yet another bestseller if it ever comes out.