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AMD Radeon HD 7950 Tahiti Pro DirectX 11 GPU Review
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Date: Jan 31, 2012
Section:Graphics/Sound
Author: Marco Chiappetta
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Introduction and Specifications

When AMD announced the Radeon HD 7970 last month, it revealed a new, ultra-powerful graphics card that snatched the single-GPU performance crown from the previous titleholder, NVIDIA’s GeForce GTX 580. AMD may have staked a claim for the fastest single graphics card with the dual-GPU powered Radeon HD 6990, but its previous flagship single-GPU powered card, the Radeon HD 6970, generally trailed the GeForce GTX 580 in real-world game performance.

Although the Radeon HD 7970 didn’t actually go on sale until a few weeks after the initial announcement, there was no doubt it would be the highest performing single-GPU based graphics card available when it finally did arrive, based on early testing. What we didn’t know was how its little brother, the Radeon HD 7950 would fare. At the time of the Radeon HD 7970’s announcement, we knew the Radeon HD 7950 would be based on the same GPU and that it would arrive a few weeks after the 7970, but its final specifications and price point hadn’t been disclosed.

As it turns out, we’ve had a couple of the cards in-house for a little while now and can finally reveal all of the juicy details. AMD has also provided a fresh set of drivers which reportedly enhance the performance of the 7900-Series cards, so we recorded another set of scores with the 7970 using the updated drivers to show how much additional performance AMD was able to wring out of its newest GPU in the few weeks since we last took a look at it.

First up, some specifications and pictures of the newly released Radeon HD 7950, followed by full set of numbers for the rabbid PC gamers among you—which we assume is everyone reading this.


AMD Radeon HD 7950 DirectX 11 Graphics Card

AMD Radeon HD 7950
Specifications & Features


 

As we’ve mentioned, the new Radeon HD 7950 is based on the same GPU found at the heart of the Radeon HD 7970, codenamed Tahiti. The chip, which is based on a totally new architecture dubbed GCN or Graphics Core Next, is manufactured using TSMC’s 28nm process and features a whopping 4.31B (that’s billion) transistors. In its full configuration, which is found on the Radeon HD 7970, the Tahiti GPU sports 2,048 stream processors with 128 texture units and 32 ROPs. On the Radeon HD 7950, however, a few segments of the GPU have been disabled, resulting in a total of 1,792 active stream processors, with 112 texture units and 32 ROPs.

The Radeon HD 7950 is also clocked somewhat lower than the 7970, although AMD has claimed the cards are highly overclockable (which we test a little later). Whereas the Radeon HD 7970’s GPU is clocked at 925MHz (according to reference specifications), the 7950’s GPU is clocked at 800MHz. With fewer stream processors and texture units, and a lower frequency, the Radeon HD 7950’s compute performance has been reduced to 2.87 TFLOPS (vs. 3.79 TFLOPS with the 7970), with texture and pixel fillrates of the 89.6GT/s and 25.6GP/s, respectively, versus 118.4GT/s and 29.6GP/s for the 7970.

The Radeon HD 7950 and 7970 share the same sized 3GB frame buffer, which connects to the GPU via the same 384-bit interface, but the memory of the 7950 is clocked lower than the 7970’s as well; 1,250MHz vs. 1,375MHz, resulting in peak memory bandwidth of 240GB/s on the Radeon HD 7950.

Although their specifications are somewhat different, because they are based on the same GPU, the Radeon HD 7970 and 7950 have identical feature sets, which include AMD’s ZeroCore Power Technology, Discrete Digital Multi-Point Audio, PowerTune, GCN, Eyefinity, Partially Resident Textures (PRT), and more. We have already covered all of the low-level technical details in our Radeon HD 7970 launch article, however, so we won’t rehash everything again here. If, however, you’d like a refresher on the technology, we’d strongly suggest giving this article a read.

  

   
The Radeon HD 7950: Up Close and Personal

As you can see in the pictures, the Radeon HD 7950 is basically identical to the higher-end 7970 (the only physical differences are their power connectors). There is a single, barrel type fan at the rear of the card, which pumps air through a heatsink with vapor chamber, which is in turn expelled through vents in the case bracket. That’s how previous Radeon HD 6900 series cards were configured as well, but with the 7970 and 7950, AMD has moved to a new fan design with larger, wider blades. The fan has been optimized for lower speed operation, but pushes more air than the previous generation. AMD also removed the stacked DVI connector present on 6900-series cards to increase the size of the exhaust vent and reduce turbulence. The Radeon HD 7970 and 7950 are also outfitted with a multi-step vapor chamber with three distinct levels. One level makes contact with the GPU, another with the memory, and the last touches the VREGs.

The fan shroud design on the 7900-Series has been tweaked as well. Unlike Radeon HD 6900 series cards which had a mostly squared, flat design that was sealed at the rear, the Radeon HD 7970 and 7950 have curved shrouds with additional vents. AMD also removed the stiffening plate from the back to maximize the amount of air-space that would be present between cards installed in adjacent PEG slots. A second-generation phase-change thermal interface material is used as well. All of these changes (along with the move to 28nm) culminate in significantly reduced temperatures over older Radeons, although the updated cooler has proven to be somewhat louder than the fansink combo used on the Radeon HD 6970.

Other physical attributes of the Radeon HD 7950 include the familiar pair of CrossFire edge connectors at the top, and the two-position BIOS switch that debuted on Radeon HD 6900 series cards. That tiny switch is used to toggle between two BIOS chips on the card—the first BIOS can be altered / updated, while the second will return the card to its factory settings (or vice versa). That’s something that might come in handy with the modding crowd, which are likely to be fond of the 7950.

Also on the top, at the far end of the card are its power connectors. Unlike the Radeon HD 7970 which requires a PCIe 8-pin feed along with a 6-pin feed, the Radeon HD 7950 has a pair of 6-pin connectors only.

Finally, the output configuration on reference Radeon HD 7950 series cards consists of one dual-link DVI output, two mini-DisplayPort outputs and a single HDMI output. Four of these outputs can be used at any given time to power displays in a multi-monitor Eyefinity configuration, but with upcoming DisplayPort hubs due to arrive in shortly, up to six displays can be connected to a single card.

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Test System and Unigine Heaven v2.5

How We Configured Our Test Systems: We tested the graphics cards in this article on an Asus P9X79 Deluxe motherboard powered by a Core i7-3960X six-core processor and 16GB of G.SKILL DDR3-1600 RAM. The first thing we did when configuring the test system was enter the system UEFI and set all values to their "optimized" or "high performance" default settings and disabled any integrated peripherals that wouldn't be put to use. The hard drive was then formatted and Windows 7 Ultimate x64 was installed. When the installation was complete we fully updated the OS and installed the latest DirectX redist, along with the necessary drivers, games, and benchmark applications.

HotHardware's Test System
Intel Core i7 Powered

Hardware Used:
Intel Core i7-3960X
(3.3GHz, Six-Core)
Asus P9X79 Deluxe
(Intel X79 Express)

Radeon HD 7950
Radeon HD 7970
Radeon HD 6990
Radeon HD 6970
GeForce GTX 590
GeForce GTX 580 3GB OC
GeForce GTX 580

16GB OCZ DDR3-1600
Western Digital Raptor 150GB
Integrated Audio
Integrated Network

Relevant Software:
Windows 7 Ultimate x64
DirectX April 2011 Redist
ATI Catalyst v12.1b/12.2
NVIDIA GeForce Drivers 290.53

Benchmarks Used:

Unigine Heaven v2.5
3DMark 11
Batman: Arkham City
Just Cause 2
Alien vs. Predator
Metro 2033
Lost Planet 2
Dirt 3

Unigine Heaven v2.5 Benchmark
Pseudo-DirectX 11 Gaming


Unigine Heaven

Unigine's Heaven Benchmark v2.5 is built around the Unigine game engine. Unigine is a cross-platform, real-time 3D engine, with support for DirectX 9, DirectX 10, DirectX 11 and OpenGL. The Heaven benchmark--when run in DX11 mode--also makes comprehensive use of tessellation technology and advanced SSAO (screen-space ambient occlusion) It also features volumetric cumulonimbus clouds generated by a physically accurate algorithm and a dynamic sky with light scattering.


The new Radeon HD 7950 performed well in the tessellation-heavy Unigine Heaven benchmark. The 7950 trailed the Radeon HD 7970 by a fair margin, but significantly outpaced the previous-gen Radeon HD 6970 and beat the GeForce GTX 580 as well.

Also note the marked improvement in the 7970's performance when using the latest RC11 drivers, versus our original scores from last month.
 
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3DMark 11 Performance

Futuremark 3DMark11
Synthetic DirectX Gaming


Futuremark 3DMark11

The latest version of Futuremark's synthetic 3D gaming benchmark, 3DMark11, is specifically bound to Windows Vista and WIndows 7-based systems due to its DirectX 11 requirement, which isn't available on previous versions of Windows. 3DMark11 isn't simply a port of 3DMark Vantage to DirectX 11, though. With this latest version of the benchmark, Futuremark has incorporated four new graphics tests, a physics tests, and a new combined test. We tested the graphics cards here with 3DMark11's Extreme preset option, which uses a resolution of 1920x1080 with 4x anti-aliasing and 16x anisotropic filtering.


The Radeon HD 7950 also performed well in the 3DMark11 benchmark. Here, the 7950 finished behind the Radeon HD 7970, but fell somewhere in between the reference GeForce GTX 580 and the factory overclocked 3GB model.

Once again, we see a small performance improvement for the Radeon HD 7970 when tested with the newer RC11 drivers.
 
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Lost Planet 2 Performance

Lost Planet 2
DirectX 11 Gaming Performance


Lost Planet 2

A follow-up to Capcom’s Lost Planet : Extreme Condition, Lost Planet 2 is a third person shooter that takes place again on E.D.N. III ten years after the story line of the first title. We ran the game’s DX11 mode which makes heavy use of DX11 Tessellation and Displacement mapping and soft shadows. There are also areas of the game that make use of DX11 DirectCompute for things like wave simulation in areas with water. This is one game engine that looks significantly different in DX11 mode when you compare certain environmental elements and character rendering in its DX9 mode versus DX11. We used the Test B option built into the benchmark tool and with all graphics options set to their High Quality values.


Although the Radeon HD 7950 performed well according to LP2, it fared a bit worse than it did in our previous two tests. Here, the Radeon HD 7950 actually trails the reference GeForce GTX 580 at the lower resolution, but comes out ahead once we cranked thing up to 2560x1600. The factory overclocked GeForce GTX 580 3GB card, however, beat the 7950 here, hands down. The Radeon HD 7970 also showed a miniscule, improvement at the higher resolution when tested with the RC11 driver.
 
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Just Cause 2 Performance

Just Cause 2
DX10.1 Gaming Performance


Just Cause 2

Just Cause 2 was released in March '10, from developers Avalanche Studios and Eidos Interactive. The game makes use of the Avalanche Engine 2.0, an updated version of the similarly named original. It is set on the fictional island of Panau in southeast Asia, and you play the role of Rico Rodriquez. We benchmarked the graphics cards in this article using one of the built-in demo runs called Desert Sunrise. The test results shown here were run at various resolutions and settings. This game also supports a few CUDA-enabled features, but they were left disabled to keep the playing field level.


Just Cause 2 paints a picture similar to the Lost Planet 2 benchmark. In this test, the Radeon HD 7950 gets beat by the reference GeForce GTX 580 at 1920x1200, but pulls ahead at 2560x1600. The factory overclocked, 3GB GTX 580, however, outpaces the Radeon HD 7950 at both resolutions in this game.

It's also worth noting that performance is ever-so-slightly decreases in JC2 when using the newer RC11 drivers with the Radeon HD 7970.
 
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Batman: Arkham City Performance

Batman: Arkham City
DirectX Gaming Performance


Batman: Arkham City

Batman: Arkham City is a sequel to 2009’s Game of the Year winning Batman: Arkham Asylum. This recently released sequel, however, lives up to and even surpasses the original. The story takes place 18 months after the original game. Quincy Sharp, the onetime administrator of Arkham Asylum, has become mayor and convinced Gotham to create "Arkham City" by walling off the worst, most crime-ridden areas of the city and turning the area into a giant open-air prison. The game has DirectX 9 and 11 rendering paths, with support for tessellation, multi-view soft shadows, and ambient occlusion. We tested in DX11 mode with all in-game graphical options set to their maximum values, at various resolutions.


Although the framerates are somewhat lower, Batman: Arkham City tells essentially the same story as Just Cause 2. In this game, the Radeon HD 7950 pulls ahead of the reference GeForce GTX 580 once the resolution is cranked up to 2560x1600, but the 7950 can't match the 3GB GeForce GTX 580, regardless of resolution.

From this point forward, we'll also be testing CrossFire and SLI performance with the Single-GPU powered cards. Unfortunately, in this first test with Batman:AC CrossFire is essentially broken. We saw some visual anomalies with the game's menu system, but the benchmark itself produced good visuals. However, performance doesn't scale properly on the Radeons.
 
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Metro 2033 Performance

Metro 2033
DirecX11 Gaming Performance


Metro 2033

Metro 2033 is your basic post-apocalyptic first person shooter game with a few rather unconventional twists. Unlike most FPS titles, there is no health meter to measure your level of ailment, but rather you’re left to deal with life, or lack there-of more akin to the real world with blood spatter on your visor and your heart rate and respiration level as indicators. The game is loosely based on a novel by Russian Author Dmitry Glukhovsky. Metro 2003 boasts some of the best 3D visuals on the PC platform currently including a DX11 rendering mode that makes use of advanced depth of field effects and character model tessellation for increased realism. This title also supports NVIDIA PhysX technology for impressive in-game physics effects. We tested the game resolutions of 1920x1200 and 2560x1600 with adaptive anti-aliasing and in-game image quality options set to their High Quality mode, with DOF effects disabled.


Metro 2033 proved to be somewhat of a strong suit for the Radeon HD 7950. In this game, the 7950 easily outpaced both flavors of GeForce GTX 580, and trailed only the 7970 and dual-GPU powered cards. The RC11 drivers also gave the 7970 a small boost in performance.


Unlike Batman: Arkam City, CrossFire worked in this game and performance scaling was very good. The Radeon HD 7950 CrossFire setup outpaced both the 6970 CrossFire and GeForce GTX 580 SLI setup without incident.
 
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Dirt 3 Performance

Dirt 3
DirectX 11 Gaming Performance


Dirt 3

Dirt 3 is the latest in a string of great racing games from Codemasters. Like is predecessor, 2009's Dirt 2, this game sports impressive visuals with DX11 support. “Ultra” settings for shadow effects, tessellation, and post processing elements, like depth of field, then become available to the gamer, and in turn, crank up the workload on the graphics subsystem. The game engine also makes use of multi-core processors for higher performance on top-end systems. We tested the game configured with its Ultra graphics options with 4X anti-aliasing at resolutions with of 1920x1200 and 2560x1600.


The Radeon HD 7950's performance in Dirt 3 mirrors that of Just Cause 2 again. In this test, the Radeon HD 7950 gets beat by the reference GeForce GTX 580 at 1920x1200, but pulls ahead at 2560x1600. The factory overclocked, 3GB GTX 580, however, outpaces the Radeon HD 7950 at both resolutions in this game.


Performance looks a little different with the multi-GPU setups in Dirt 3. In a two-card configuration, the Radeon HD 7950 offered very good scaling and outpaced the GeForce GTX 580 SLI rig at both resolutions.
 
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Alien vs. Predator Performance

Alien vs. Predator
DirectX 11 Gaming Performance


Alien vs. Predator

The Alien vs. Predator benchmark makes use of the advanced Tessellation, screen space ambient occlusion and high-quality shadow features, available with DirectX 11. In addition to enabling all of the aforementioned DirectX 11 related features offered by this benchmark, we also switched on 4X anti-aliasing along with 16X anisotropic filtering to more heavily tax the graphics cards being tested.



The Radeon HD 7950 had no trouble outpacing all of the other single-GPU powered cards in Alien vs. Predator, save for the higher-end Radeon HD 7970. The dual-GPU powered cards, however, maintained a significant lead. Also note, the RC11 drivers gave the 7970 a nice performance boost here.


CrossFire also scaled properly in this game and the Radeon HD 6950 CrossFire rig trailed only the dual-card Radeon HD 7970 setup.
 
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Overclocking, Noise, Temps

With AMD touting the overclockability of the Radeon HD 7950, we were curious to see how much frequency headroom the card had left in the tank, with a 4+ billion transistor, ultra-complex 28nm GPU under the hood. So, for our next set of performance metrics, we spent some time overclocking the new Radeon HD 7950 using the Overdrive utility built into ATI's Catalyst drivers. 

AMD Radeon HD 7950 Overclocking
Cranking Things Up A Notch

For these tests, we simply cranked PowerTune up to the +20 mark and increased the GPU and memory frequencies until we saw visual artifacts or our test system exhibited instability. Turns out, the Radeon HD 7950 had no trouble whatsoever running at a GPU clock of 1.05GHz with 1275MHz memory. Although, in all honestly, we’re pretty sure there was some more headroom left in the memory, but due to time constraints we ran with these numbers.

With the Radeon HD 7950’s GPU overclocked to over 1GHz, it put up numbers somewhat better than the Radeon HD 7970 in the JC2 benchmark and just missed the mark set by the higher-end card in AvP. All told, performance increased by a respectable 15% - 17.6% with some simple tweaks. With more extensive cooling and tweaking, we’re confident even higher frequencies will be possible with the Radeon HD 7950.

While testing, we also spent some time monitoring noise and temperatures under various workloads and found the Radeon HD 7950 to be quieter than the 7970, but not quite as quiet as NVIDIA’s offerings. The Radeon HD 7950’s quieter operation is due to the card’s much lower stock frequency. Shave 125MHz off the top and disable a few functional blocks in the GPU and it’s no wonder the 7950 is somewhat more subdued acoustically, versus its higher-end counterpart. Temperatures were also pretty good. The Radeon HD 7950 idled at 43’C and peaked at 74’C. Although these numbers aren’t that far off from other high-end GPUs, what we did notice about the 7950 was that it was much cooler to the touch after prolonged use. The Radeon HD 6970, for example, was almost untouchable after a couple of hours in the test bed. The Radeon HD 7950, however, was warm (obviously) but was easy to handle.
 

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Total System Power Consumption

Before bringing this article to a close, we'd like to cover a few final data points--namely power consumption and noise. Throughout all of our benchmarking and testing, we monitored acoustics and tracked how much power our test system was consuming using a power meter. Our goal was to give you an idea as to how much power each configuration used while idling and while under a heavy workload. Please keep in mind that we were testing total system power consumption at the outlet here, not just the power drawn by the graphics cards alone.

Total System Power Consumption
Tested at the Outlet

Quite simply, the Radeon HD 7950's power consumption characteristics were the best of the group. Both idle and load / peak power were below all of the other cards we tested. That wouldn't mean much if the card offered middling performance, but it was the second fastest, single-GPU powered card in the group, finishing behind only the Radeon HD 7970 most of the time, though the GeForce GTX 580 did have its moments.
 

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Our Summary and Conclusion

Performance Summary: There are a few facets of performance to cover in this summary; the Radeon HD 7950’s performance versus its main competition, the performance improvements offered by the latest AMD Catalyst drivers, and the performance of the various multi-GPU configurations we tested.

Let’s start with the drivers. In preparation for this article, AMD sent over the latest Catalyst driver suite that not only added support for the Radeon HD 7950, but reportedly offered performance improvements for the 7970. With that in mind, we re-ran all of our numbers on the Radeon HD 7970, but kept our original scores in the graphs to illustrate any performance gains related to the new drivers. As the numbers showed, in the majority of tests, there were measurable gains to be had with the RC11 drivers. In the conclusion of our Radeon HD 7970 launch piece, we mentioned that AMD was likely to be able to wring more performance from their new architecture as their software engineers got more familiar with GCN, and that seems to be coming true already. We suspect similar performance gains are likely with future driver releases as well. The Radeon HD 7900 series’ performance a few months from now, will likely be significantly better than what we’ve shown you on the previous pages.

Versus its main competition, the new Radeon HD 7950 performed well. In the vast majority of tests, the Radeon HD 7950 outperformed a reference GeForce GTX 580 and it blew the doors off the Radeon HD 6970. In comparison to a factory overclocked, 3GB GeForce GTX 580, however, the Radeon HD 7950 traded victories. Of course, the higher-end Radeon HD 7970 cemented its position as the current fastest single-GPU based graphics card around.

CrossFire performance was generally good, but there are concerns in this area. A couple of months out from the release of the highly anticipated Batman: Arkham City and CrossFire is still broken in that game. AMD had made great strides over the last few years not only in supporting new games with CrossFire, but also offering excellent performance scaling, but two month out and Batman still doesn’t scale properly and we’re sure there are other games as well. In all fairness though, in the other games we tested, CrossFire appeared to work properly, performance scaled as expected, and the Radeon HD 7950 CrossFire setup put up some impressive numbers.


The AMD Radeon HD 7970 and 7950 Look Virtually Identical.

The AMD Radeon HD 7950 should be available immediately through boutique system builders and popular on-line retailers, with wider availability in the coming weeks. The suggested price for the card is $449. At that price, the Radeon HD 7950 undercuts reference GeForce GTX 580 cards by a few bucks ($20-$40) and custom, overclocked GeForce GTX 580 with 3GB frame buffers by about $80-$100. Clearly, with the release of the Radeon HD 7950, which offers better performance and more features, GeForce GTX 580 pricing needs to come down to remain competitive.

With that said, we wished AMD was more aggressive with Radeon HD 7900 series pricing. The Radeon HD 6970 and 6950 debuted at $369 and $299, respectively. The Radeon HD 7970 and 7950 arrive at $549 and $449. In light of competing offerings, the 7900 series is technically priced “right”, but we would have loved to see AMD come out of the gate with more aggressive pricing to make the cards more attainable for more enthusiasts and to put more pricing pressure on its main rival, NVIDIA.

Ultimately though, the Radeon HD 7950 is the card to beat at its price point, even if we wish it was a little lower. The card offers cutting edge features, excellent power consumption characteristics, performance is strong, and the thing is highly overclockable. We suspect anyone who springs for a Radeon HD 7950 will be very pleased by what it has to offer.

  • Strong Performance
  • Good Power Consumption
  • Highly Overclockable
  • 3GB Frame Buffer
  • Eyefinity Support
  • Pricey
  • Trades Victories With 3GB GeForce GTX 580 OC



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