XFX Radeon HD 6950 XXX Edition Review

Author: Chris Ledenican
Editor: Howard Ha
Publish Date: Thursday, April 28th, 2011
Originally Published on Neoseeker (http://www.neoseeker.com)
Article Link: http://www.neoseeker.com/Articles/Hardware/Reviews/XFX_HD_6950_1GB/
Copyright Neo Era Media, Inc. - please do not redistribute or use for commercial purposes.

When AMD launched their second-generation DX11 architecture, they effectively increased the memory capacity found on graphics cards in certain segments of the market. They did this by introducing a 1GB frame buffer to their mid-range Barts based graphics cards, while increasing the memory capacity of their high-end models to 2GB. This allowed products such as the HD 6950 and HD 6970 to scale incredibly well with increased setting and resolutions.

However, in today's PC gaming market a 2GB frame buffer is not necessarily going to improve gaming performance for users playing on a monitor with a maximum resolution of 1920x1080. Additionally, with most PC titles being either ported to or from a console version, there is lesser incentive for 1080p gamers to require a graphics card with a 2GB frame buffer. For these reasons, AMD gave their AIB partners flexibility when it comes to the included memory capacity of Cayman based graphics.

One such model to receive a memory overhaul is the XFX HD 6950, which features a 1GB frame buffer. This reduces the memory capacity to 50% of the reference design, but to reduce any negative impact, XFX increased the GPU clock and memory speeds to 830MHz and 1300MHz, respectively. This could increase the overall performance, and depending on the settings, the XFX model could easily outperform the reference boards due to the higher clock speeds. The XFX HD 6950 also includes an enhanced thermal solution featuring dual intake fans and a large heatsink with integrated copper heatpipes.

When dealing with a graphics card that has a reduced frame buffer, the general rule is that it will not perform at the same level as card with a 2GB frame buffer when gaming at higher resolutions. The question is exactly how much of an impact will the reduction have on this model. To investigate this, we are going to pit the 1GB XFX HD 6950 against the reference board and see how they compare in resolutions up to 2560x1600. This should give us a good understanding of how the 1GB model fits into the market, and if the reduced price is ultimately worth it in the long run.

 

Specifications
Bus Type
PCI-E 2.1
GPU Clock
830MHz
Memory Bus
256
Memory Type
GDDR5
Memory Size
1024 MB
Memory Speed
5200 MHz
Thermal Solution
Fansink
Minimum Power Supply Requirement
500 Watt
Outputs
DVI, HDMI, Dual-Link DVI
Card Dimensions
10.08 x 4.38 x 1.5
Features
Directx 11 support, DirectCompute 11, Open CL, Eyefinity Technology, Shader Model 5.0, OpenGL 3.2, Windows 7, Mini-DisplayPort 1.2, HDMI 1.4a
Warranty
Lifetime (Limited)

Unlike the Barts based graphics cards, the Cayman architecture uses a newly redesigned core architecture that has dual graphics engines, new compute features and a modified VLIW4 core architecture. The Cayman core now features 24 SIMD engines, which give it a maximum of 96 texture units. In addition. the render-ends have been upgraded for better Anti-Aliasing performance, and it has a 256-bit GDDR5 memory interface. This allows it to support memory speeds up to 5.5Gbps.

One of the more dramatic changes to the Cayman architecture is the switch from the VLIW5 to VLIW4 design. Previous generation AMD graphics cards utilized a VLIW5 engine that had 4 simple and 1 complex processing units. This design worked well, but its utilization wasn't necessarily very efficient.  The new VLIW4 engine now features 4 units that have equal capabilities, and a "T" unit where the functions are distributed throughout it. This improves the ALU and Raster utilization, which in turn increases the overall efficiency of the design over the previous generation's architecture. The new design allows more SIMD engines to be placed in the same space, which improves the overall efficiency per millimeter by about 10%.

The Cayman architecture uses a similar geometry engine to that of the previous generation graphics cards, but with the HD 6900 series AMD has effectively doubled it. This gives both the HD 6970 and HD 6950 dual graphics engines, allowing them to process two primitives per clock, giving it twice the transform, backface cull and tessellation sub-division rates. This improves the DX11 tessellation performance, which is highlighted in the next slide.

With the redesigned architecture of the Cayman GPU, the HD 6900 series has up to three times the tessellation performance in comparison to Cypress based graphics cards.

PowerTune is a new power management system that is being introduced with the AMD 6900 series, and will continue to be in future AMD graphics products. In essence, PowerTune is a means to set a predefined TDP by adjusting the clock speeds in real time. The way in which PowerTune is utilized is very different than the on-board regulation chips seen on NVIDIA’s 500 series. NVIDIA’s power management system monitors the power coming from the rails, while AMD’s technology instead relies on performance counters that are embedded throughout the GPU. These performance counters have an internal algorithm that can dynamically calculate how much power is being used, and adjust accordingly. This allows PowerTune to maintain the power draw at the predefined level, effectively eliminating huge surges in power from occurring. Since games operate at a lower peak power rate than benchmarking utilities such as Kombuster, in-game performance will not be negativity affected.

EQAA or Enhanced Quality Anti-Aliasing is new as of the 6900 series, and is an AA option that improves in-game image quality by effectively doubling the amount of coverage samples. According to AMD, the performance loss while it is enabled is minimal.

With the release of the Cayman architecture, AMD has maintained support for their new Morphological-AA, which is essentially implemented in the same manner as it was in the 6800 series. Morphological Anti-Aliasing is an AA method that uses a post process filtering technique with DirectCompute. This approach can deliver full screen Anti-Aliasing, faster super sampling and is compatible with DX9 through DX11 games. In addition, Morphological-AA can be used alongside MSAA to ensure the best image quality without losing any in-game detail.

Another noteworthy feature is AMD's HD3D technology. Stereoscopic 3D support is not new to the market, and in fact Nvidia has employed 3D support in products for some time now. What is new, however, is AMD's approach to the technology. Whereas Nvidia uses a closed-sourced method to drive Stereoscopic 3D, AMD is using an open-source method that allows many manufactures to create their own means of support. This means that there will not be a specific standard between compatible 3D displays, glasses and software, but rather multiple options available to the consumer. Still, this is in the early stages and it could be some time before AMD's HD3D technology will see widespread adoption.

The XFX HD 6950 comes packaged in a box with an industrial motif that features an image of a dual-fan cooling solution. In the middle of the two fans, XFX has listed the product model along with the memory capacity and type of PCIe interface. At the bottom right of the packaging are three small icons that once again list the included memory, as well as the model series and support. The back of the box has additional details about the cards.

The accessories are found in the top portion of the inner packaging,and include a CrossFire connector, driver CD and various forms of documentation. This is a bit bare for a high-end card, but at least XFX included a CrossFire connector.

Visually, the HD 6950 XXX edition graphics card is quite stunning. This is due to the inclusion of a large black heatsink shroud that has silver accents and two centralized 80 mm fans. There are three copper heatpipes that extend out of the board, which further increases the overall visual appeal of the card. To be sure, the dual fans and large heatsink will improve both the thermal and acoustic performance of the card. This model utilizes a slightly smaller PCB that measures 10.08 inches in length, and occupies dual expansion bays.

As an XXX edition model, this card comes with increased GPU and memory frequencies of 830MHz and 1300MHz (5.2Gb/sec effective), respectively. Other than the memory capacity and overclocked settings, the rest of the specifications are stock for a Cayman Pro GPU, which gives this model 22 SIMDs, 1408 ALUs and 88 texture units, making for over 2 TFLOPs of gaming performance.

The back of XFX HD 6950 XXX Edition graphics card shows off the card's clean layout. The board includes dual 6-pin power connectors, two CrossFireX bridge connectors, eight memory chips and a front mounted voltage regulation area. One feature we did not like, however, was the use of warranty stickers placed on two of the GPU retention screws. This means that if the user removes the heatsink to apply an after-market TIM or heatsink, they will void the card warranty. This is the first card we have seen from XFX to include warranty stickers on the GPU screws, but it appears to be a growing trend in the industry.

With two CrossFireX bridge connectors, the XFX HD 6950 XXX edition graphics card can support mutli-GPU scaling up to Quad-Fire. When adding additional graphics cards the performance is greatly increased and with the 6000 series, AMD has really stepped up their CrossFire performance. Adding more cards to the system also increases the total frame buffer available, which could be quite the incentive for consumers to purchase this model over the more costly 2GB cards- it would be cheaper to add a second or third HD 6950 to a system for improved gaming performance.

One feature that is noticeably missing from this card is the dual BIOS toggle switch. This means that if you flash this card and something goes wrong, there is no easily recoverable BIOS option. So if your looking to flash your card to a HD 6970, you might want to purchase a model that does include the dual BIOS switch.

The XFX HD 6950 XXX has a total PowerTune rating (TDP) of 200W and a 140W typical gaming power rating. The card requires dual 6-pin power connectors to supply adequate power to the board. It is recommended that a power supply of at least 500W be used when running a single HD 6950 graphics card, and of course a PSU with a higher power capacity rating will be needed if the card is used in a CrossFire configuration.

The rear video options on the XFX HD 6950 XXX include a HDMI 1.4a port, dual version 1.2 Mini-DisplayPorts, one SingleLink-DVI port, and a DL-DVI port. The DP ports used on the 6000 series cards feature a higher bandwidth and refresh rate, which allows each port to support Stereoscopic 3D, A/V and even multiple displays through a single port. The HDMI port is also updated to support the latest technologies, and the 1.4a connection now adds support for stereophonic 3D via AMD's HD3D Technology.

The XFX HD 6950 XXX edition graphics card uses a custom dual-fan heatsink that is attached to a 10 inch black PCB. This gives the card better overall cooling and acoustics than the reference model, while being nearly half an inch shorter. The dual fans on the cooler are both 80mm in size, and share a single PWM fan header. Since both the fans use the same connection they will spin at the same RPM at all times. The heatsink sits directly below the dual-fan solution and is attached to the board via four screws that surround the GPU.

The heatsink itself consists of a dense aluminum array that has a surface area of nearly 9 inches. The cooler also has three copper heatpipes that connect the base to the array and use a very efficient direct contact design. The overall design of the heatsink is very robust, and with the dual intake fans the XFX HD 6950 XXX graphics card should offer excellent thermal performance.

The XFX HD 6950 XXX uses a custom board layout that includes a 4+1 front phase design, eight 128MB HYNIX memory chips and a centrally mounted Cayman graphics processors. The GPU is built on a 40 nm process at TSMC Taiwan with a die size of 389mm², and packs in 2.64 billion transistors. To improve the thermal performance, XFX has included a heatsink on the VRM, which will reduce the temperature and allow more airflow to safely travel to the GPU.

 

Overclocking:

The memory and GPU frequencies of the XXX Edition graphics card ship with overclocked settings, however with the GPU only being increased by 4% over the reference design there was still plenty of additional headroom. In our labs we were able to pump up the GPU clock speed to an impressive 955Mhz, which is an increase of nearly 15% . To achieve this and still maintain stability, we had to increase the core voltage to 1299mV, but with the dual fan thermal solution the XFX card could easily operate on such a high power rating. The memory also scaled very well, as our card was able to reach a maximum stable rating of 1430MHz (5.7Gb/sec effective). We were extremely pleased with the overclocking headroom of the XFX XXX Edition graphics card, and we should see some impressive scaling across our benchmarks with such high clock speeds.

Hardware Configuration:

Drivers:

ATI cards released prior to the 6800 series will be tested using AMD's Catalyst 10.8 drivers, while the 400 series NVIDIA graphics cards will be tested using their 260.89 drivers. All card released after the 6800 series will be used with their release drivers.The GTX 590 was tested with with Nvidia's 297.59 driver.

We are in the process of retesting all of our graphics cards with the latest drivers and should have the results ready within the next few weeks. For AMD we are using their early release of the 11.4 driver, while we are using Nvidia's 270.51 driver for testing.

Benchmarks DX11:

Benchmarks DX10:

Test Settings:

All in game benchmarks were performed at resolutions of 1280x1024, 1680x1050, 1920x1200 and 2560x1600. Vsync is disabled in the control panel, the AA is set to x4 with AF set to x16 and all the in-game settings are turned up to high.

Usage:

Our current power usage testing consists of using Unigine Heaven 2.1 to gauge the power requirement and temperature of the graphics cards. The program applies a very heavy load to the GPU. For the minimum temperature and power consumption the system will be left in an idle state for 15 minutes and for load we will run Unigine in its entirety at the highest settings.

We are changing the way we gauge power consumption and are currently in the process of testing the new method. Instead of using a program designed to stress a GPU to the maximum level, we are going to use the Crysis Warhead benchmark on high settings. We will set the benchmark to run through multiple levels and record the average peak power rating. This will give use real-world results as opposed to just stressing the graphics card to the max. Once we have all of our graphics cards tested using the new method we will update our reviews.

We are also moving our test system over from a open air bench-table to a closed chassis. This will also give us results that are more inline with the average user. Like with the power ratings these results will be ready soon and we will update the reviews to reflect the new readings as soon as they are ready.

 

Comparison Specifications AMD:

 
AMD Radeon HD 6870
AMD Radeon HD 6850
ATI  Radeon
HD 5750
ATI Radeon HD 5770
ATI Radeon HD 5830
ATI Radeon HD 5870
AMD Radeon HD 6950
AMD Radeon HD 6970
Processing Cores
1120
960
720
800
1120
1600
1408 1536
Core Clock
900MHz
775MHz
700MHz
850MHz
800MHz
850MHz
800MHz
880MHz
Memory Clock
1050MHz
1000MHz
1150MHz
1200MHz
1150MHz
1200MHz
1250MHz
1375MHz
Memory Interface
256-bit
256-bit
128-bit
128-bit
256-bit
256-bit
256-bit
256-bit
Memory Type
1GB GDDR5
1GB GDDR5
1GB GDDR5
1GB GDDR5
1GB GDDR5
1GB GDDR5
2GB GDDR5
2GB GDDR5
Fabrication Process
40nm
40nm
40nm
40nm
40nm
40nm
40nm
40nm

 

Comparison Specifications Nvidia:

 
Nvidia GeForce GTS 450
Nvidia Geforce GTX 460 FTW
Nvidia GeForce GTX 470
Nvidia GeForce GTX 480
Nvidia GeForce GTX 560 Ti
Nvidia GeForce GTX 570
Nvidia Geforce GTX 580
Processing Cores
192
336 448 480 384 480 512
Core Clock
783MHz
850MHz
607MHz
700MHz
822MHz
742MHz
782MHz
Memory Clock
900MHz
1000MHz
837MHz
924MHz
1002MHz
950MHz
1002MHz
Memory Interface
128-bit
256-bit
320-bit
384-bit
256-bit
320-bit
384-bit
Memory Type
1GB GDDR5
1GB GDDR5
1.25GB GDDR5
1.5GB GDDR5
1GB GDDR5
1.25GB GDDR5
1.5GB GDDR5
Fabrication Process
40nm
40nm
40nm
40nm
40nm
40nm
40nm

3DMark Vantage is the stunning sequel to 3DMark 06. Futuremark's benchmarking programs have always been at the center of every bragging match. The best way to show that you've got the greatest gaming rig, is to show that you've got the highest 3DMark score. Vantage does just that. It puts your system through a series of strenuous tests, and provides you with a score to brag about!

The 1GB frame buffer did slightly reduce the HD 6950 XXX's overall performance in 3DMark Vantage, but the results were still very close to those of the 2GB card. Also, performance increased significantly once we overclocked the XFX card, as it was able to achieve higher scores than the 2GB model in each test run.

Futuremark's latest 3DMark 2011 is designed for testing DirectX 11 hardware running on Windows 7 and Windows Vista the benchmark includes six all new benchmark tests that make extensive use of all the new features in DirectX 11 including tessellation, compute shaders and multi-threading.

The results in 3DMark 11 are similar to what we saw with Vantage. At stock, the XFX HD 6950 XXX Edition graphics card is slightly slower than the 2GB model, but once overclocked it easily outperforms it.

Unigine Heaven became very popular very fast, because it was one of the first major DirectX 11 benchmarks. It makes great use of tessellation to create a visually stunning...heaven.

Unigine 2.1 doesn't appear to be affected by the reduced memory buffer, as the XFX graphics card was able to achieve a higher frame rate than the 2GB model across all the tested resolutions.

Aliens vs Predator is a DX11 Benchmark that runs though a scene straight out of the classic 80’s movie, Aliens. Since it uses DX11, it can often be more than a graphics card can handle.

As you can see from the chart, Aliens vs Predator performs better with high clock speeds as opposed to more memory. This allowed the XFX model to outperform the reference HD 6950 at both stock and overclocked settings.

DiRT 2 is the sequel to Colin McRae: Dirt and it was one of the first games to incorporate DX11 features such as tessellation, accelerated high definition ambient occlusion and Full Floating point high dynamic range lighting. This makes it a perfect game to test the latest DX11 hardware.

We are seeing the same type of results in DiRT 2 that we did in Aliens vs Predator. Essentially, what is happening is that most games perform the same with either a 1GB or 2GB frame buffer with our test settings applied.

Lost Planet 2 is a sci-fi action-adventure game from CAPCOM that puts players on a fictional planet called E.D.N. III 10 years after the events of the first game. Like the other new games added to our reviews, Lost Planet 2 includes support for DX11 features to enhance the lighting, charters and environments.

Lost Planet 2 uses a lot of in-game tessellation and requires massive memory bandwidth to perform at its best. This being the case, the 1GB XFX card did not perform at the same level as the reference model. However, once overclocked the XFX card was able to surpass the 2GB card, even with the resolution at 2560 x 1600.

Metro 2033 puts you right in the middle of post apocalyptic Moscow, battling Mutants, rivals and ratio-active fallout. The game is very graphics intensive and utilizes DX11 technology, making it a good measure of how the latest generation of graphics cards performs under the latest standard.

Metro 2033, like Lost Planet 2, requires a large frame buffer to run at its best. As a result, the 1GB model does take a performance hit when playing the most demanding games on the market.

Total War: Shogun 2 is a game that creates a unique gameplay experience by combining both real-time and turn-based strategies. The game is set in 16th-century feudal Japan and gives the player control of a warlord battling various rival factions. Total War: Shogun 2 is the first in the series to feature DX11 technologies to enhance the look of the game, but with massive on-screen battles it can stress even highest-end graphics cards.

The XFX graphics card was able to achieve a higher frame rate at the two lower resolutions, but at 1920x1200 and above the memory limitations reduced the performance to below that of the 2GB reference model.

F1 2010 is a video game based on the 2010 season of the Formula One world championship and is a mutli-console port. It was developed by Codemasters and released released in September 2010 for the PC, PS3 and Xbox 360, with the PC version including DX11 features.

With the most graphic-intensive games out of the way, the XFX graphics card is once again performing better than the 2GB reference model.

Dragon Age II is a role-playing video game created by Bioware's Edmonton studios and is a follow up to the highly successful original Dragon Age: Origins. In this game players take the role of Hawke, who has just fled fled the nation of Ferelden with his family after it was destroyed. The PC version of Dragon Age II includes DX11 features such as tessellation for enhanced geometric detail and Compute shader for post process rendering like blur, bloom, film effects.

Dragon Age II is yet another title that prefers the XXX Edition's higher clock speeds over the reference model's 2GB frame buffer.

Batman: Arkham Aslyum mixes extraordinary visuals with great gameplay, in order to make an excellent benchmark. It's not a stressful as Crysis, but it can still push cards to their limits.

The 1GB XFX model really underperformed here. In all the tested resolutions it was only able to keep pace with the GTX 460, which was quite surprising

Crysis Warhead is one of the most graphically intensive games on the mainstream market. It's graphically breathtaking, and can bring any system crashing to it's knees.

The XFX HD 6950 XXX Edition graphics card displayed excellent results in Crysis Warhead, especially in the three lower resolution settings.

Just Cause 2 places you in Panau, Southeast Asia as Agent Rico Rodriguez. The game is a third-person shooter that pits you against countless enemies with the opportunity for plenty of environment destruction. With explosions and gun fire galore, this game is perfect for testing out the latest hardware.

Our last benchmark has the XFX 1GB model easily outperforming the 2GB reference model at all the tested resolutions.

Temperature:

To measure core GPU temperature, MSI's Kombustor was used. The idle temperature was taken after leaving nothing running for up to 15 minutes. The load temperature was taken 15 minutes after starting Kombuster for Multi-Core graphics cards

For a high-end graphics card the XFX HD 6950 XXX was able to maintain excellent thermal performance, which as due to its robust cooling solution. Also, with the dual 80mm fans the XFX model was extremely quite even during our load testing.

Power Usage:

To measure power usage, a Kill A Watt P4400 power meter was used. Note that the above numbers represent the power drain for the entire benchmarking system, not just the video cards themselves. For the 'idle' readings we measured the power drain from the desktop, with no applications running; for the 'load' situation, we took the sustained peak power drain readings at the end of a 30 minute Kombustor run.

The XXX edition graphics card had a slightly higher maximum TDP than the reference model due to the higher clock speeds, but the difference was only 11W. Once we overclocked the GPU though the power usage jumped to 420W, which was due to the fact that we increased the voltage to 1299mV.

Conclusion:

The 1GB Radeon HD 6950 is an interesting product, as it is essentially the equivalent of the Radeon HD 5830 for AMD’s second generation DX11 GPU family. However, the 1GB HD 6950 largely succeeds where the HD 5830 failed. This is due to the fact that the HD 5830 had lackluster performance in comparison to the other models in the HD 5800 series, which prevented it from ever living up to its full potential.

The 1GB HD 6950 on the other hand has roughly the same performance as the reference 2GB model, but in most cases it retails for $30 to $40 less. Even more impressive was that the XFX HD 6950 XXX Edition graphics card was able to perform equal to its 2GB counterpart in resolutions up to 2560x1600 in most of our benchmarks. The only few exceptions were the most demanding games in our test bench, such as Lost Planet 2, Metro 2033 and Total War: Shogun II.

In addition to the excellent stock performance, the XFX HD 6950 XXX Edition graphics card had plenty of overclocking headroom, which even further increased the overall performance level. Out of the box, the HD 6950 XXX has a 4% factory overclock, which does improve the performance over the reference design, but with XFX only increasing the clock by 30MHz they left plenty of headroom. In our testing we were able to increase the GPU clock speed by an additional 15% to 955Mhz. With our custom settings, the XXX edition graphics card scaled very well across the board, and in many benchmarks it performed as well as products in a higher price bracket.

The custom thermal solution used on the XXX edition graphics card is another excellent aspect of this model. To cool the Cayman Pro GPU, XFX uses a large heatsink that utilizes dual 80 mm propeller blade fans. This design supplies ample airflow at low decibel levels, decreasing the overall acoustics in comparison to the reference models. Still, even with the reduced noise output the robust heatsink used with the XXX edition card still has excellent thermal performance.

The cooling solution on this model was in large part the reason we were able to push the GPU clock speed up to 955MHz. With the core running at a low temperature, we are able to increase the power rating to 1399mV, which allowed us to overclock the XFX model higher than any HD 6950 we have tested prior to this model. Even with the overclocked settings and increased voltage, the dual 80 mm fans kept the overall acoustics low.

There were only a few real downsides to this card. The custom clock speeds and thermal solution increase the retail price of this model. While this is hardly surprising in the case of factory overclocked graphics cards, the additional premium commanded by the XXX Edition card makes it the same price as the 2GB models. We were also disappointed to see that XFX has removed the dual BIOS toggle switch. This is a relatively small complaint, but since the dual BIOS is one of our favorite aspects of the 6900 series, it would have been nice to see it on this card.

Overall, the XFX 6950 XXX edition graphics card proves that a 2GB frame buffer is indeed overkill for the majority of PC gamers. Additionally, with this model XFX has included an excellent cooling solution that performs better than the reference model at both the thermal and acoustic levels. These all make the XXX edition graphics card a great high-end gaming product, but ultimately, it’s our opinion that the $269 MSRP is just slightly too high for a small 4% overclock. Still, we highly recommend this graphics card due to its high performance and excellent thermal solution.

»Neoseeker.com

Copyright Neo Era Media, Inc., 1999-2014.
All Rights Reserved.

Please do not redistribute or use this article in whole, or in part, for commercial purposes.