by Alexey Stepin , Yaroslav Lyssenko
04/01/2011 | 11:00 AM
Nvidia’s introduction of its new GF114-based graphics card didn’t shatter the market of performance-mainstream products priced at about $250, yet the GeForce GTX 560 Ti did provoke some inconveniences for AMD’s graphics department. The Radeon HD 6950, although competitive to Nvidia’s new card in sheer speed, cost $299 whereas the Radeon HD 6870, priced at the same level as the GeForce GTX 560 Ti, was inferior to the latter in performance. AMD must be given credit for producing a quick response, though. Two responses, actually. The company has dropped the price of the Radeon HD 6870 from $239 to $219 and has released a cheaper ($259) version of Radeon HD 6950. We are going to talk about this latter card in this review, so here are some more details about it.
The amount of memory that gaming graphics cards carry on board was growing up linearly along with the progress in consumer-oriented 3D technologies. At one time, this was a crucial parameter, and one of the most frequently asked questions went like “do I need more megabytes of graphics memory to have a faster frame rate?” Graphics cards progressed from 64 megabytes to 1 gigabyte with stops at 128, 256 and 512 megabytes. So, that’s where we are at now. 1 gigabyte of graphics memory is enough for 99 percent of applications and usage scenarios, especially as more and more gaming projects are developed for multiple platforms and thus have lower requirements regarding this parameter. There are exceptions, though. The senior models of the GeForce GTX 500 series come with more onboard memory due to their memory controller configurations that employ 320 and 384-bit memory buses.
However, AMD endowed its Radeon HD 6900 products with 2 gigabytes of graphics memory, making them more expensive to manufacture. As a result, the Radeon HD 6950 turned to be less competitive than it might be. Fortunately, the company realized its mistake quickly enough, so the new Radeon HD 6950 version priced at $259 comes with 1 gigabyte of memory, retaining the rest of the specs of its more expensive cousin.
We’ve got PowerColor's version of the new Radeon, so we can have a chance to check out if 2 gigabytes of graphics memory is redundant for a modern top-end graphics card.
PowerColor ships its HD6950 1GB in an upright box like the one with the HD6870 PCS+ card that we tested earlier. The only difference is the picture on the face side which is reminiscent of the Warhammer 40K universe.
That’s not the most popular of game settings, but it’s a matter of taste. The box design is neither original nor informative. You can only see the card’s model name as well as the type and amount of its graphics memory.
There is a simple cardboard tray inside the box, which is not much in terms of protection. Besides the graphics card in an antistatic pack, we found the following in there:
The accessories are even scantier than those of the HD6870 PCS+. There is even no CrossFire bridge here. On the other hand, the lack of accessories helps lower the price of the product which, along with performance, is the crucial factor for the majority of users.
Oddly enough, the PowerColor HD6950 1GB uses a slightly revised Radeon HD 6870 design rather than the reference Radeon HD 6950 PCB developed by AMD. We saw this very PCB in our review of the HD6870 PCS+:
There are some discrepancies, of course, but we can’t see them until we take off the cooler by unfastening the four spring-loaded screws:
There are actually but a few differences from the HD6870 PCS+. We can see a slightly different wiring of the ground in the back part of the PCB and some changes in the top left corner due to the second CrossFire connector and BIOS switch. PowerColor engineers seem to have made the most of the resources they already had at hand.
The 4-phase GPU voltage regulator is based on a CHiL Semiconductor CHL8214 controller whereas the memory subsystem is based on a controller from uPI Semiconductor marked as uP1509P. The overall design of the power circuit hasn’t changed. It still represents the 4+2 formula and receives external power via two 6-pin PCIe 1.0 connectors.
Hynix’s 1Gb H5GQ1H24AFR memory chips (32 Mb x 32) are installed on the PowerColor card. Their T2C suffix denotes a rated frequency of 1250 (5000) MHz which is indeed the frequency the card clocks its memory at, delivering a peak bandwidth of 160 GBps. We don’t expect these chips to be good at overclocking but the PowerColor HD6950 1GB already seems to have enough of memory bandwidth to begin with.
The card’s GPU was manufactured on the 49th week of 2010. Of course, it is a cut-down version of the Cayman processor with only 1408 ALUs active out of the total 1536 available in the GPU die. Thus, there are only active 352 VLIW4 processors out of the total 384. The texture-mapping subsystem is reduced from 96 to 88 TMUs whereas the rasterization subsystem has remained intact because the memory controller configuration depends on it. So, the 32 raster back-ends available in the GPU die are all active here.
The GPU clock rate is 250 MHz in power-saving mode and 800 MHz at full load, which complies with AMD’s official Radeon HD 6950 specs. The GPU voltage can be set at one of three values: 0.898, 1.0 or 1.063 volts, depending on the operation mode. There is a BIOS switch in the top left of the PCB which allows switching between the read-only factory BIOS and the rewritable version that can be modified by the user.
You can see a standard configuration of interfaces on the mounting bracket of the PowerColor HD6950 1GB: two DVI-I ports, one HDMI and two mini-DisplayPorts. You can use all five simultaneously. And if you employ a DP 1.2 switch, you can even make the card output visual content to as many as six monitors. The two CrossFire connectors allow building a top-performance multi-GPU subsystem consisting of up to four such cards. Perhaps the recently released Radeon HD 6990 doesn’t make such a quad-GPU configuration very appealing, yet some users might want to use this opportunity.
As we noted in our PowerColor HD6870 PCS+ review, that card’s cooling system was very poor or downright defective. The HD6950 1GB comes with a similar cooling solution:
The heatsink is larger but there are still only two heat pipes. There are two 92mm fans to blow at the heatsink. We’d call this cooler promising if we hadn’t had a disappointing experience with the PowerColor HD6870 PCS+. Let’s check it out anyway.
It is the first Radeon HD 6950 product with 1 GB of video memory in our lab, so we decided to check out its power consumption as well. We used the following testbed:
The new testbed for measuring electric characteristics of graphics cards uses a card designed by one of our engineers, Oleg Artamonov, and described in his article called PC Power Consumption: How Many Watts Do We Need?. As usual, we used the following benchmarks to load the graphics accelerators:
Except for the maximum load simulation with OCCT, we measured power consumption in each mode for 60 seconds. We limited the run time of OCCT: GPU to 10 seconds to avoid overloading the graphics card's power circuitry. Here are the obtained results:
The power consumption measurements do not tell us anything new. The PowerColor HD 6950 1GB needs somewhat more power than the reference Radeon HD 6950 2GB in 2D mode and when decoding HD video. When it comes to 3D applications, its power draw is somewhat lower. 161 watts is comparable to the power consumption of the GeForce GTX 560 Ti, so the PowerColor card is quite competitive in its class in this respect.
Take note that in the video playback mode the numbers reflect the peak power consumption as is clear from the diagram above whereas the average is about 40 watts. The second power connector (it is closer to the PCB edge and is labeled “12V 6-pin” in the table) has a higher load than the first one, but even OCCT cannot load those connectors much higher than their recommended limit of 75 watts.
Now let’s check out the performance of the card’s cooler. We've got the following results at an ambient temperature of 25°C:
The results are far from extraordinary and do not actually differ much from those of the PowerColor HD6870 PCS+ but the HD6950 1GB has higher heat dissipation. Besides, the cooling system of the PowerColor HD6950 1GB looks very good in comparison with the reference card's cooler.
The PowerColor HD6870 PCS+ would produce a lot of noise in our tests. Is the new card from PowerColor any better in this respect?
Oddly enough, this depends on the position of the BIOS switch. When you use the read-only factory BIOS, the noise level is within reasonable limits. At a background noise of 38 dBA, the PowerColor HD6950 1GB is as good as the reference Radeon HD 6950 2GB in terms of noisiness in 3D applications. But when the switch is set into the other position, the fans accelerate and get much louder. This looks like some protection against overheat during overclocking experiments. The high level of noise can hardly keep off true overclockers, so we don't mind the manufacturer's cautious approach. Of course, we ran the card in the b1 mode (i.e. with the factory BIOS) in our tests, including the temperature tests.
The PowerColor HD6950 1GB didn’t do particularly well in our overclocking tests. We managed to make it stable at the following clock rates:
The GPU frequency of 860 MHz is hardly a big success but we achieved a rather high memory frequency of 5400 MHz. We are going to benchmark our PowerColor HD6950 1GB both at its default clock rates and at the frequencies we achieved in our overclocking attempt.
We are going to investigate the gaming performance of PowerColor Radeon HD 6950 1 GB using the following universal testbed:
We used the following ATI Catalyst and Nvidia GeForce drivers:
The ATI Catalyst and Nvidia GeForce graphics card drivers were configured in the following way:
Below is the list of games and test applications we used during this test session:
First-Person 3D Shooters
Third-Person 3D Shooters
Semi-synthetic and synthetic benchmarks
We selected the highest possible level of detail in each game. If the application supported tessellation, we enabled it for the test session.
For settings adjustment, we used standard tools provided by the game itself from the gaming menu. The games configuration files weren’t modified in any way, because the ordinary user doesn’t have to know how to do it. We ran our tests in the following resolutions: 1600x900, 1920x1080 and 2560x1600. Unless stated otherwise, everywhere, where it was possible we added MSAA 4x antialiasing to the standard anisotropic filtering 16x. We enabled antialiasing from the game’s menu. If this was not possible, we forced them using the appropriate driver settings of ATI Catalyst and Nvidia GeForce drivers.
Besides PowerColor Radeon HD 6950 1 GB, we also tested the following products:
Performance was measured with the games’ own tools and the original demos were recorded if possible. We measured not only the average speed, but also the minimum speed of the cards where possible. Otherwise, the performance was measured manually with Fraps utility version 3.3.2. In the latter case we ran the test three times and took the average of the three for the performance charts.
Quite expectedly, the Radeon HD 6950 is in no way affected by the loss of half the graphics memory, except for its lowered price. The PowerColor performs confidently both at the default and overclocked frequencies. When overclocked, it can even challenge the more expensive GeForce GTX 570. The game is playable at every resolution except for 2560x1600 which calls for a higher-class graphics card.
There is no difference between the two Radeon HD 6950 models, which indicates that there is no need in the larger amount of graphics memory. The GeForce GTX 560 Ti is ahead but not as much as to be definitely preferable to the Radeon HD 6950, especially as the latter can be accelerated through overclocking.
This game isn't a problem for today's graphics cards but we can see that the GeForce GTX 560 Ti has the lowest bottom speed whereas both versions of Radeon HD 6950 maintain it at a high level even in the Ultra-HD modes. There is even no need to overclock them.
This is the only test so far in which we can see any difference between the two versions of Radeon HD 6950. However, the difference is small and we see it only at 2560x1600 where both versions are too slow. The PowerColor card looks preferable to the GeForce GTX 560 Ti because ensures a playable frame rate in the Full HD mode. You can have the same performance with the GeForce GTX 570 but it would cost you more.
This game is tested with the tessellation option turned on.
Overclocking is unrewarding for our Radeon HD 6950 in this game, yet it is only inferior to the GeForce GTX 570. 1600x900 is the only resolution where we can see a difference, so there is no need to buy the more expensive card. Take note that the bottom speed fluctuates wildly when the tessellation option is turned on.
This game runs with enabled tessellation.
We don't gain much from overclocking, especially as the Radeon HD 6950 copes with the game at 1920x1080 even at its default frequencies. Together with the GeForce GTX 560 Ti, the Radeon HD 6950 1GB seems to be the best performance-mainstream graphics card available today.
Again we don’t see any reasons to prefer the 2GB version of Radeon HD 6950. The 1GB version is just as good throughout the entire range of display resolutions. Overclocking doesn’t make much sense, either, although the overclocked Radeon HD 6950 1GB overtakes the GeForce GTX 570 at 1600x900.
Lost Planet 2 prefers Nvidia's Fermi architecture, so AMD's solutions are not competitive here. Even the Radeon HD 6950 can only deliver a playable frame rate at 1600x900 and our overclocking wasn’t enough to improve the situation.
Bioware’s new RPG was featured in Radeon HD 6990 ads and for a good reason: Crysis Warhead has finally got a match in terms of hardware requirements. The overall picture is just the opposite to Lost Planet 2: Nvidia's solutions are not competitive to AMD's Cayman-based products. If the highest graphics quality settings are selected, the PowerColor card allows playing at 1600x900, which is quite an achievement considering the poor performance of the GeForce GTX 570, for example. Like in the rest of our games, except for Crysis Warhead, we can see no difference between the two versions of Radeon HD 6950 which differ in the amount of graphics memory.
We enforced full-screen antialiasing using the method described in our special Mass Effect 2 review.
Here, our overclocking helps the PowerColor card overtake the GeForce GTX 560 Ti at 1600x900 and leave it behind at the higher resolutions. On the other hand, it is fast enough for comfortable play in every display mode, including Ultra HD, even without any overclocking. Like the GeForce GTX 560 Ti, the PowerColor HD6950 1GB is surely an excellent choice for playing Mass Effect 2.
The PowerColor is also good in this Formula 1 simulator. It delivers a higher speed than the GeForce GTX 560 Ti and is close to the more expensive GeForce GTX 570.
StarCraft II is perhaps the only game so far where our overclocking is rewarding as it improves the speed of the PowerColor HD6950 1GB at 2560x1600, making the game more comfortable to play at that resolution. Overall, the Radeon HD 6950 1GB is almost as good as the GeForce GTX 570.
The game engine makes us choose between FSAA and the full selection of special effects. We prefer to enable all of the special effects at the expense of FSAA.
The bottom speed of the GeForce GTX 560 Ti is very poor although its average frame rate is comparable to that of the Radeon HD 6950 1GB. So, the latter card is preferable for playing this game unless you can afford a GeForce GTX 570. Take note that none of the tested cards can deliver a playable frame rate at 2560x1600.
We minimize the CPU’s influence by using the Extreme profile (1920x1200, 4x FSAA and anisotropic filtering). We also publish the results of the individual tests across all resolutions.
The two versions of Radeon HD 6950 do not differ much whereas our overclocking of the PowerColor card isn't good enough to improve its score seriously. As a result, the GeForce GTX 570 remains unrivalled, followed by the GeForce GTX 560 Ti and Radeon HD 6870.
The same goes for the individual tests. The GeForce GTX 560 Ti is not as far behind the Radeon HD 6950 in the second test as in the first, the two cards being equal to each other at 2560x1600.
We use the Extreme profile here. As opposed to 3DMark Vantage, this profile uses a resolution of 1920x1080 pixels.
The two Radeon HD 6950s with different amounts of graphics memory deliver the same performance in this benchmark. Unlike in 3DMark Vantage, our overclocking makes the PowerColor card almost as fast as the GeForce GTX 570.
This benchmark makes wide use of tessellation to render the surface of the earth. The number of polygons per one frame can be as high as 1.5 million!
As opposed to the Radeon HD 6800, the Radeon HD 6900 series flies higher, yet not as high as the Nvidia Fermi solutions which have more advanced tessellation units. The performance of the PowerColor card is quite high in itself even at 2560x1600 but our overclocking isn’t rewarding.
We use Normal tessellation in this test.
Despite its less advanced tessellation resources compared to the Fermi solutions, the Radeon HD 6950 is almost as fast as the GeForce GTX 570. Moreover, the bottom speed of the GeForce GTX 560 Ti plummets at resolutions of 1920x1080 and higher, making the PowerColor card even more competitive in this test.
As it might have been expected, the reduced amount of onboard graphics memory does not affect the performance of the Radeon HD 6950. It is only at the resolution of 2560x1600 in Crysis Warhead and StarCraft II that we could spot a small performance degradation that amounted to a mere 9 and 6%, respectively. Thus, the two versions of Radeon HD 6950, with 1 GB and 2 GB of onboard memory, are in fact equals in today’s games.
Is there any point in buying the more expensive version? It does not offer any benefits for games because most of them are quite satisfied with 1 gigabyte of onboard graphics memory. Perhaps there are some GPGPU applications that might put 2 GB of memory to use, but you may want a specialized professional solution in that case.
It is clear that the Radeon HD 6950 2GB can hardly survive in the gaming market. Priced at $299, it is squeezed between the faster GeForce GTX 570 and the less expensive GeForce GTX 560 Ti. The Radeon HD 6950 1GB fits this niche much better, being cheaper than the former and faster than the latter solution from Nvidia. You can see that in the summary diagrams:
First of all, the Radeon HD 6950 1GB can boast an advantage of 8-30% over the GeForce GTX 560 Ti, depending on the resolution. We even see a twofold advantage in some applications which are obviously optimized for AMD products. The new card is also 3-10% behind the GeForce GTX 570, depending on the resolution. Again, the gap can be as large as 40% in certain situations, so you should check out the performance of the cards in the particular games you are going to play. As for overclocking, our sample of the PowerColor card got 2 to 14% faster at the overclocked frequencies, depending on the game and resolution.
Talking about PowerColor’s version of Radeon HD 6950 1GB that we used in our tests, we can say that it’s really worth its price. Although it cannot boast high overclockability or rich accessories, it delivers high performance in today’s games and has acceptable thermal and noise characteristics. In other words, the PowerColor HD6950 1GB is a regular graphics card without extraordinary features, yet also without obvious downsides. It can be recommended to every gamer who's shopping in the sub-$300 category.