Introducing AMD’s HD 6970 and HD 6950

AMD Graphics and Nvidia are locked in a perpetual battle to one up each other in what can only be described as a “graphics war”. Nvidia had issues with introducing their Fermi DX11 architecture and video cards and AMD beat them to the market by over six months with the first DX11 video cards about this time last year. In April of this year, Nvidia launched their GTX 470 and GTX 480 which were criticized for being hot-running, power-hungry and loud although they offered somewhat higher performance than AMD’s HD 5870 and HD 5850.  It appears that AMD actually believed that Fermi was unfixable.

However, a few months later, Nvidia’s midrange GTX 460 turned out to be a very successful reworking of GF100 Fermi into GF104 that scaled well, ran cool, had good thermal characteristics, overclocked well and no doubt ate into AMD’s then DX11 90% marketshare. To combat GTX 460, AMD released their HD 6000 series codenamed “Barts” with HD 6870 and HD 6850 being debuted this past October. This is not AMD’s high end, codenamed “Cayman”, which has just arrived, but rather their upper-midrange which was renamed from HD 58×0 series and is designed to take on and surpass the GTX 460 and all of its variants.  Now we see that the new HD 6970 and HD 6950 are designed to combat Nvidia’s brand new reworked GF110 which debuted since the HD 68×0 launch as thermally tamed and quiet-running GTX 580 and GTX 570 video cards which significantly surpass the HD 58×0 series’ performance.

ABT was represented by this editor at AMD’s Press Day at the famous LA Exchange in October and saw AMD’s vision unfold further for us. Since we are going to focus on the HD 6970 and the HD 6950’s performance in 23 games, we will only give you the barest outline of their 5 hour presentation which covered “Barts”, “Cayman” and the future “Antillies” graphics cards. We do see that the reason that they chose downtown Los Angeles is symbolic of their increasing commitment to the movie industry and they have partnered up with several Hollywood movie studios to increase productivity by using AMD hardware and know how. They also used the presentation to introduce their support for 3D in PC gaming and 3D for video playback.

AMD’s Press Event was called “Believe Your Eyes” and they laid out their vision for the world’s press. AMD feels that Fusion is uniquely suited to conquer the world and they stress the “firsts” they have accomplished, including being first to bring DX11 GPUs to market very quickly and successfully. They are quite proud of their marketshare and do not intend to allow Nvidia to make inroads.  AMD points out the advantages of their Eyefinity which now allows more displays to be driven off of a single card – up to six displays now with a hub adapter – rather than with Nvidia’s competing Surround solutions which require two similar video cards running in SLI to power 3 displays.

A rose by any other name …

Today, AMD Graphics is proud to introduce an improved version of their successful HD 58×0 series with better performance, but now as the new HD 69×0 series and on the same 40 nm process as the 5000 and 68×0 series. The advantage is higher performance at lower prices. AMD appeared intent to go after Nvidia’s GTX 480 by offering more performance at a similar price. However, they apparently did not appear to expect GTX 5×0 successfully meeting Nvidia’s goals of reworking GF100 Fermi into GF110.  AMD still holds on to the title of fastest video card with their dual-GPU HD 5790 although it trades blows with GTX 580 in many games, losing in the tessellation-heavy games or where CrossFire does not scale.

Here is our interview with Stanley Ossias of AMD. He gives an insight into their strategy but it does appear that they did not expect the GTX 580 to so successfully address its issues, nor did they appear to expect GTX 570 before their own Cayman launch.

However, AMD is not abandoning their strategy as it has worked for AMD in the past and they call it “aiming for the sweet spot”. The HD 6000 series will also support a more flexible form of Eyefinity than the 5000 series, and it is also going to support 3D PC gaming and 3D video playback. What may be confusing to many is that HD 6870 and HD 6850 are slower than HD 5870 and HD 5850 respectively and yet are replacing them. AMD’s goal is to give more gamers the ability to experience HD 58×0-type performance in a less expensive, smaller and even less power-hungry video card.  On the other hand, the HD 6970 is AMD’s fastest single-GPU card and the true successor to their successful HD 5870, just as the HD 6950 replaces the HD 5850. In many ways, a picture is worth 1,000 words and here is AMD’s continuation of their video card strategy:

We still see changes only to the upper midrange and at the high end. AMD is continuing the HD 5700 series for now; unchanged, as they evidently feel unchallenged by Nvidia’s GTS 450 which we reviewed here against HD 5750. In the above chart, we see the HD 5800 series diverge into 3 streams – the “Antilles”, an “X2” video card at the highest end as a successor to the current dual-GPU HD 5970; the “Cayman” launching today, which is using AMD’s fastest single GPU to succeed and surpass the Cypress HD 5870 and we have been expecting that it would take on Nvidia’s GTX 480 video card.

Here is the latest round of our testing of the HD 5870 versus the GTX 480 in our reviews here (overclocked versus super-overclocked). You can follow the links backward through several other of our GTX 480 vs. HD 5870 testing, back to our first testing of these cards in April. We can see that the GTX 480 is consistently faster than even the overclocked HD 5870 PCS+ and there is some need for AMD to address this with a faster and also more efficient GPU.  The new HD 6950 is the Cayman video card that was designed beat Nvidia’s formerly second fastest video card, the GTX 470.

With this launch, AMD has been directly targeting the just now discontinued Nvidia’s GTX 480.  Things move very quickly in the graphics card world.  So now, the HD 6970 (SEP $369.00) will take on the GTX 480 and the brand new GTX 570; and the HD 6950 (SEP $299.00) is said to be in a class of its own, and appears to be similar in performance to the current HD 5870.  This is AMD’s opinion of the way the graphics market stands at this moment and there is no mention of the GTX 470.  At any rate, we will examine the performance of the HD 6970 and HD 6950 and compare them to their closest competition to determine their value in a no-holds barred performance showdown with 13 graphics cards and 25 gaming benchmarks.

What’s new in HD 69×0?

Since “seeing is believing” is AMD’s theme for the 6000 series launch and it is all about the 3 “eyes”, we shall briefly cover them here:

• Eyedefinition
• Eyefinity
• Eyespeed

Under Eyedefinition, we see a further subdivision with more efficient tesselation; there is mention of a Barts tweaked engine, offering up to 2x the tessellation performance of the HD 58×0 GPUs – an area where AMD was perceived weak in comparison to Nvidia’s Fermi GPUs in heavily tessellated benchmarks and games.   With Cayman we see the potential for a further increase of geometry performance and we also see mention of enhanced architecture for efficiently using GPU compute and for improvement and performance in games. We also note improvements in Anisotropic Filtering (AF) and new Anti-Aliasing modes – morphological AA and EQAA.

The HD 69×0 series features 2x DVI ports and one HDMI port plus two mini-DisplayPorts which are DP version 1.2.

This is important because of the new Eyefinity features that now allow for daisy chaining of displays and for using a new hub, much like using a USB hub, to output to six displays from a single card!

Eyespeed refers to GPU compute and to AMD’s “open initiative” approach to (everything and especially to) OpenCL, in contrast to Nvidia’s use of their own proprietary GPU language, CUDA. We see AMD partnering with Cyberlink, Arcsoft, Viewdle, Adobe, Microsoft and more companies (some of which are also Nvidia’s partners) to bring you, the end consumer, quality video processing and playback; and of course, UVD 3 accelerated decoding for 3D BluRay playback.

In our HD 68×0 launch article, we evaluated AMD’s claim of 35% better performance per mm over HD 58×0 and found that the HD 6870 is about equal in performance to HD 5850 overall. Not really too much has architecturally changed from Cypress except that Barts has up to 2x the performance of the tessellator in the HD 58×0 GPU.  Here is the Barts GPU from AMD’s own presentation slide.

We were able to confirm that tessellation was superior in Barts over Cypress in Tessellation-heavy games and engines; in Lost Planet 2 and in Unigine’s Heaven, we saw the weaker-performing HD 6870 beat the generally faster HD 5870.  And now we see that Cayman has been further improved over Barts and Cypress .

We note that there are dual-graphics engines and the Radeon’s VLIW5 core architecture has been replaced by the more efficient VLIW4 using 24 SIMD engines in the HD 6870 and 96 texture units.  Overall efficiency will be improved over both Barts and Cypress.

There is a complete core redesign with a more efficient VLIW4 thread processing that is more efficient that the previous VLIW5 design.

The Render Back-Ends have necessarily been upgraded and AMD has enhanced the GPU Compute as described below.

To see what it brings new, we note that the UVD engine has been updated; HDMI 1.4a is available for 3D Blu-ray and we see an improved Tesselator Engine. AMD now uses a second Ultra Threaded Dispatch Processor and an improved engine logic. We have noted in previous reviews, that Nvidia’s Fermi GPUs are faster in heavily tessellated scenes than competitive AMD Cypress GPUs. Well, now AMD claims a solid tessellation improvement over Cypress and HD 58×0 series and calls their method “tessellating the right way”.

In the case of Barts, it was supposed to be twice more efficient than the Cypress HD 5870 and now Cayman’s HD 6970 is supposed to be three times more efficient.  Here is AMD’s slide off their own internal testing.

Of course, we have to test this out to see what it means in a practical way for us gamers.

Morphological Adaptive AA

AMD’s new morphological anti-aliasing technique works as a post process effect. In other words, the GPU finishes rendering each frame as usual – but before presenting it to the display, it runs it through another shader pass to perform the filtering. This differs from traditional multi-sample and super-sample AA techniques where the filtering occurs during the rendering of each frame. In fact, this technique can eliminate aliasing for still images, though it’s intended to work better when in motion.

The filter works by first detecting high contrast edges with various pixel-sized patterns that are normally associated with aliasing, and assumes they should actually be straight lines that are not aligned to pixel edges. It then estimates the length and angle of the ideal line for each edge, and determines the proportional coverage by the lighter and darker color for each pixel along the edge. Finally it uses this coverage information to blend the colors for each pixel. All of this is actually being accomplished by the Catalyst drivers through a DirectCompute shader while the Local Data Share is used to keep adjacent pixels in memory for a low overall overhead. It will be interesting to see if AMD chooses to extend this morphological adaptive AA to the 5000 series as there is no reason it cannot be done, except perhaps to differentiate HD 6000 series from the current one.

AMD’s diagrams (below) should help to illustrate how this is accomplished.

Since the edge detection step requires frequent sampling and re-sampling of adjacent pixel colors, it offers a lot of opportunities for data re-use by using the LDS (Local Data Share) hardware to avoid redundant data fetches and to significantly improve performance. AMD sent us a driver very late in our testing and we are unable to evaluate it as yet. We simply cannot comment on what we have not yet evaluated.

Enhanced Quality Anti-Aliasing (EQAA)

EQAA is a new anti-aliasing option available on the AMD Radeon HD 6900 series. It offers enhanced quality over standard Multi-Sample Anti-Aliasing (MSAA) modes by doubling the number of coverage samples per pixel, while keeping the same number of color/depth/stencil samples. This technique offers advanced smoothing of aliased edges without requiring additional video memory, and with a minimal performance cost.

The new Enhanced Quality Anti-Aliasing modes can be enabled by selecting the 2xEQ, 4xEQ, or 8xE modes that have been added to the anti-aliasing slider in AMD Catalyst Control Center. EQAA is fully compatible with all other supported anti-aliasing techniques, including Adaptive AA, Super-Sample AA, Custom Filter AA (Edge-Detect), and Morphological AA.  Selecting the Enhance Application Settings option from the drop-down box will cause applications that natively support MSAA modes to use equivalent EQAA modes instead.

Selecting the Override Application Settings option will force applications to use EQAA modes if they are selected on the slider; this setting will often work even if an application does not natively support antialiasing.

The following table lists the number of color/depth/stencil and coverage samples used by the available MSAA and EQAA modes:

Anisotropic Filtering (AF)

With the HD 5000 series, AMD brought genuine angle-independent filtering to gaming by putting an end to angle-dependent deficiencies. The AMD Radeon HD 6900 series continues to support fully angle invariant anisotropic filtering, and incorporates further improvements in LOD precision relative to the ATI Radeon HD 5000 Series. These image quality benefits come with no additional performance cost and remain enabled at all Texture Filtering Quality settings.

However, our own Senior Editor BFG10K pointed out the flaws in AMD’s Anisotropic filtering with the transitions, here, here and here. AMD listened to us and the enthusiast community and they have improved the transitions between filter levels. Well, examining these improvements are beyond the scope of this performance evaluation, but rest assured that BFG10K will again provide the definitive answers in a future review right here at ABT.

AMD PowerTune™ Technology

AMD PowerTune is a new technology that attempts maximum performance at TDP. It allows the GPU to be designed with higher engine clock speeds which can be applied on the broad set of applications that have thermal headroom. AMD PowerTune technology helps enable higher performance that is optimized to the thermal limits of the GPU by dynamically adjusting the engine clock during runtime based on an internally calculated GPU power assessment. AMD PowerTune technology also helps to improve the mechanism to deal with applications that would otherwise exceed the GPU’s TDP.  In other words, like Nvidia’s power limiter, they do not allow a power virus such as FurMark to exceed a predetermined limit.

AMD PowerTune allows for the GPU to run within its TDP budget at higher clock speeds than otherwise possible by managing the engine clock speeds based on calculations which determine the closeness of the GPU to its TDP limit. In other words, it will not throttle the GPU when TDP is exceeded, as abruptly.

AMD’s PowerTune technology can be directly adjusted by the user using the AMD Catalyst Control Center, AMD Overdrive tab.  PowerTune can be tweaked to more aggressively limit power and heat or be used by enthusiasts to squeeze every last bit of performance out of the Cayman GPU in overclocking.

AMD PowerTune technology dynamically adjusts the performance profile in real time to fit within the TDP envelope.

Architectural improvements

Like Cypress, all Barts and Cayman GPUs are produced with the 40 nm process. AMD’s new reference Radeon HD 6970 has 1536 Stream Processors with its core operating at 880 MHz with 2GB of GDDR5 at 5.5 GHz (880/1375 MHz) on a 256-bit bus. There are 32 ROPs and 96 Texture units. The Radeon HD 6950 should perform similarly to the Radeon HD 5870 due to architectural refinements and fine-tuning. The HD 6970’s maximum load board power is 250 watts (and 190 Watts with Power Tune; “typical gaming power” – see explanation above) and its idle is 20 watts matching the idle of the HD 6950. The HD 6950 requires two 6-pin PCIe power connectors (bottom card) and the HD 6970 uses 6-pin+8-pin connectors.

Here is the specification chart for the HD 6970:

The new AMD Radeon HD 6950 is clocked at 800 MHz with 2GB of GDDR5 at 4 GHz on a 256-bit bus and features 1408 Stream Processors. There are also 32 ROPs. Maximum load board power is 200 watts and the idle is at 20 watts. The reference HD 6850 is 11 inches long and only requires two 6-pin PCIe power connectors (top card, above).

Here are the HD 6950’s specifications:

To properly bring you this review, we are using our reference Diamond HD 5870 (850/1200 MHz) as our standard and we put all of our Radeon cards through their paces this week with the very latest release drivers – Catalyst 10-12.  We noticed that the overall performance in our benchmark suite dropped slightly from using Catalyst 10-10 with HD 5870, but stayed the same or very slightly increased with our HD 6870.  H.A.W.X. 2 performance significantly increased the most of any game that we tested using either the Radeon HD 5870 or the HD 6870 just from upgrading to Catalyst 10-12.

Here are nine of the thirteen cards that we are testing today for you:

Other Improvements

AMD has not forgotten the enthusiast community.  Flashing a BIOS incorrectly can lead to despair so AMD has enabled a toggle switch for a Dual BIOS option for a factory default BIOS that a user can always fall back on by flipping a switch.  It is a nice feature.

AMD is continuing to use and refine their vapor chamber cooling for several years.

Imitation is the sincerest form of flattery and Nvidia has just begun to use vapor chamber technology and their own diagram demonstrates how it works with their newest GTXes.

We are comparing the new HD 6970 and the HD 6950 to the HD 5870, the HD 6870, the HD 6850, and we brought back an oldie – the HD 4870 to see what an upgrade might be like. In the same way, we are comparing 13 cards total, including the GTX 280 for the same reasons that we are including the HD 4870 – to see how performance has increased over the past 2-1/2 years or so.  We will also use the the EVGA (super-overclocked) and Galaxy GTX 460-1GB (at stock clocks), plus the (stock-clocked) Galaxy GTX 460-768MB version. We are directly comparing the new Caymans with GTX 480/570/580 to see how performance varies over a wide spectrum of video cards from both vendors – from $500 down to below $200.  We are using Nvidia’s very latest WHQL GeForce 263.09 drivers that also give performance increases over the previous version, so both vendors are giving us their very best for this review.

Specifically, you will see us pit our HD 5870 against the new HD 6970 and HD 6950 as well as the HD 6870 and HD 6850 and also against Nvidia’s reference GTX 480, the GTX 570, 3 GTX 460 variants and the “oldies”, GTX 280 and HD 4870. We benchmark 23 modern games and 2 synthetic benchmarks using 1680×1050, 1920×1200 and/or 2560×1600 resolutions. Since we are using the fastest of the fast upper-midrange video cards, it makes sense to test at the highest resolutions that they can handle and with the most demanding settings. We shall also overclock our Cayman HD 69×0 cards to give you an idea of what AMD’s board partners will soon be bringing you.

Is AMD’s rival, Nvidia’s overclocked GTX 580 worth $140 or so more than the HD 6970?

Since Nvidia has signaled their willingness to engage in a price war by dropping their GTX 460’s and 470’s pricing to a bit below AMD’s new cards, we naturally want to know if the new AMD HD 69×0 cards are worth their prices as they compare to the $350 GTX 570 and the $500 GTX 580. The new Caymans are certainly priced very competitively and we will show you where it comes down to performance and features.

Overclocking

Unfortunately, the overclock on our HD 6970 can best be described as “mild” – from 880/1375 MHz to 920/1475 MHz.   It was not stable at 925 MHz and we had some issues with the unseasonably warm temperatures in our testing lab that appproached 80F.  Also, the overclock on our HD 6950 was held back by Catalyst Control Center (CCC) which allowed only a +40 MHz overclock on the core at default settings.  Athough the HD 69×0’s +40 MHz core overclock may be perceived as disappointing, it will give you an idea of scaling while still keeping your own overclocking expectations realistic. We only used CCC to set our Radeon overclocks and we did not increase the core voltage nor change the fan profile and we tested in a very warm environment that could be described as “Summer-like”.

Because of severe time constraints on this article, HD 6000 series CrossFire will be examined in depth in a further article as well as 3-panel Eyefinity (which can be driven off of a single Radeon) verses Nvidia’s competing Surround which requires SLI to make it work. We used our Intel Core i7-920 at 3.8 GHz for this evaluation so there was no chance of any CPU bottlenecking. Read on to see our test bed and the games we used.

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«1. Introduction2. Test Configuration3. Vantage4. F.E.A.R.5. X3 - Terran Conflict6. ET:QW7. CoD48. UnrealTournament39. Batman10. Grand Theft Auto IV11. Serious Sam (2010)12. Mafia II13. Call of Juarez14. Lost Planet15. Crysis16. Far Cry 217. Just Cause 218. H.A.W.X.19. Resident Evil 520. Call of Pripyat21. BattleForge22. AvP23. Dirt 224. Metro 203325. Lost Planet 226. H.A.W.X. 227. Heaven 2.028. Performance Summary & Overclocked Results29. Conclusion30. View All»