Sapphire HD 7970 6GB Vapor-X GHz Edition Review

ccokeman - 2012-08-05 16:43:03 in Video Cards
Category: Video Cards
Reviewed by: ccokeman   
Reviewed on: September 27, 2012
Price: $599


Lately it has seemed that Sapphire has been cranking out the custom cards left and right to satisfy the needs of those who want something that is a bit better than the reference design in terms of cooling and reliability. As AMD's largest partner, Sapphire has the ability to deliver more than than just a reference solution with a sticker on it. In the Vapor-X line we have looked at the Vapor-X HD 7950, Vapor-X HD 7970 3GB and Toxic Edition HD 7970. After looking at what Sapphire brought to the table with the Toxic Edition HD 7970 6GB card, Sapphire reached a new pinnacle with its custom 12 layer PCB, voltage check points load monitoring LEDs, Black Diamond Chokes a massive Vapor-X cooling solution, 6GB of GDDR5 memory, highly binned silicon and the list goes on.

Surprisingly Sapphire went back to the well with this version of the Vapor-X-equipped HD 7970 GHz Edition 6GB card by incorporating just about all of the feature set of the Toxic Edition with a core that does not go through all of the time consuming binning process. Even without the top end binning on the GPU core, the GHz Edition base line feature set is enough to satisfy the needs of a great many with a "Boost" clock of 1100MHz at the touch of the EZ OC button. Sapphire's Vapor-X HD 7970 GHz Edition 6GB card is equipped with Sapphire's own "Dynamic Power suite" that includes a ten phase power design, double sided Black Diamond Chokes, and DirectFET technology mounted on a 12 layer PCB all topped off with a Vapor-X cooler capable of dissipating any thermal load the card can throw at it and keep the Tahiti XT core alive and cool to fight another day.

The 6GB frame buffer is going to up the price point to around $599 or about a $130 premium over the 3GB frame buffer version and $80 less than the limited "Toxic " Edition. Targeted at the multi screen gamer, the Vapor-X HD 7970 6GB card should offer up an increase in performance when the texture count starts to soar. Let's see where this Vapor-X rendition falls in terms of performance especially since we know the cooling is in good hands.

Closer Look:

Sapphire's packaging takes its cues from the Vapor-X cooling used on the card. The arctic theme of "Ruby's" attire is changed for effect and lets you know up front the cooling on this card is one of the predominant features. With the Vapor-X moniker you know the cooling is going to be well under control. Along the bottom of the front panel is a list of the features that include dual fans, AMD Cool and Quiet, Eyefinity 2.0 support, AMD APP acceleration and that this card uses AMD's 28nm GCN core. Over to the right side is a more specific feature set listing a Dual BIOS feature activated with the EZ OC button, Vapor-X cooling, and Eyefinity support of up to four displays. The 6GB frame buffer is highlighted in the top right corner. On the back side of the package the AMD and Sapphire feature set is detailed in order on the right with a short description on what makes up the Sapphire Vapor-X HD 7970 6GB. At the bottom of the left side is a listing of the awards Sapphire has earned over the years due to its innovative solutions.









Inside the outer sleeve is a standard cardboard box that is without any of the artwork of the packaging sleeve. Sapphires environmental concerns with the inner and outer packaging state that 100% recyclable materials are used in the packaging. Inside the box are two level; the top level contains a formed cardboard shell that houses the Vapor-X HD 7970 6GB while the lower level has a box full of the accessory bundle.



Much like we have seen with the Vapor-X line up the bundle is substantial and includes just about everything you would need to get the Vapor-X 6GB edition up and running. Included in the bundle on the documentation side is the product manual, Sapphire registration guide, and the driver disk. The hardware portion of the bundle includes a six foot HDMI cable, a pair of dual 4-pin molex to 8-pin PCIe power adapters, a CrossfireX bridge connection, Mini DP to DVI adapter, Mini DisplayPort to DisplayPort adapter and a DVI to VGA adapter. Connectivity is covered for the vast majority of users.



Sapphire's Vapor-X cooling solution works using a simple concept in a high tech package. The basic premise is that a medium (pure water) is used to transfer the heat load away from the core through vaporization where it is cooled and condenses back to a liquid state. At this point the liquid returns to the heat source through capillary action in the wicking medium to follow the process again. What allows the water to vaporize at lower temperatures is that the vapor chamber works in a very low pressure state allowing the water to vaporize earlier. Below is a graphic that illustrates the process.


Sapphire's Vapor-X cooling is a known commodity but how about the rest of the card? Let's see what Sapphire has put together and how it looks with a detailed look at what makes up the rest of the Vapor-X edition 6GB card.

Closer Look:

What you get when you step up to the Sapphire HD 7970 6GB Vapor-X Edition is a card that appears visually to be a carbon copy of the next level up Toxic Edition card from Sapphire. The small difference in appearance is by way of the Vapor-X stickers instead of the Toxic Edition stickers on the hub of the dual sealed fans. The most identifiable feature of the card is the large dual fan-equipped Vapor-X cooling solution. Sapphire's HD 7970 6GB Vapor-X Edition is built from a base that includes AMD's 28nm Graphics Core Next architecture for use in a PCIe 2.0/3.0 16x slot. At 11 inches in length, the card should fit within the confines of most of the mid/full towers on the market. The Vapor-X cooling solution is going to occupy 2.5 slots and may interfere with running a CrossfireX setup on some motherboards.

From the front the large cooling solution takes center stage with the Vapor-X logo strategically placed on each fan hub. The rear view shows a full cover back plate that functions as both a brace for the 12 layer custom PCB and as a heat sink for the 3GB of GDDR5 memory that sits on the back of the PCB. The Vapor-X logo is present in a bold text that will be visible through a chassis window. Cutouts in the back plate open around large components including the back half of the ten phase power circuit using Black Diamond chokes that run 10% cooler and 25% more efficient than reference designs. The bottom view shows that the cooling solution employs four heatpipes that transfer the thermal load from the vapor chamber base to the fin array. Along the top of the card is the Sapphire logo that lights up white when the card is in operation.











Connectivity options for the Sapphire HD 7970 6GB Vapor-X Edition includes the standard for the HD 79XX series pair of Dual Link DVI ports, a single HDMI 1.4a port that offers support for Deep Color, 7.1 High Bitrate Audio, and Stereoscopic 3D, and a pair of Mini Displayport 1.2 ports that support the use of an MST hub or daisy chaining DisplayPort monitors to allow the card to support up to six displays in an Eyefinity setup. Eyefinity 2.0 brings along the ability to have independent audio streams for each video so you can have independent video streams with audio that follows along with each one. The venting on the I/O bracket is not going to allow a ton of air through it but will help to discharge a percentage of the thermal load while the rest will be recycled into the chassis airstream for removal by the case fans. Most modern chassis have adequate airflow to minimize the effects of the open shroud design dumping heat into the chassis. The back view shows part of the VRM circuit and the voltage control and monitoring chip. The dual cooling fans are connected to separate headers on the 12 layer PCB instead of connecting to single header and splitting up under the shroud.



Along the spine of the card are some of the interesting features of the HD 7970 6GB Vapor-X Edition. Dual Crossfire bridge connections allow up to four cards to be connected in a CrossfireX configuration using a motherboard that supports this feature. The large Vapor-X cooling solution will make this configuration a difficult proposition but using the cards with a water cooling system you can enjoy a quartet of these cards. Just under the Crossfire Bridge connections is a series of LEDs used to indicate the temperature state of the GPU with green, amber, and red LEDs as a visual clue as to how warm the GPU core is getting. The HD 7970 had a dual BIOS switch mounted just aft of the CrossfireX connections that allowed the end user to have two BIOS profiles to switch back and forth as need be or to recover from a bad flash. On the GHz Edition cards that feature a boost clock the switch still functions much the same but allows for an increased clock speed. Stock GHz Edition cards have a stock clock speed of 1000MHz on the core and a dynamic boost clock of 1050MHz. The EZ OC button jumps the base clock to 1050MHz with a dynamic boost clock of 1100MHz. When activated this button glows a bright Sapphire Blue. The true test of its worth is a boost in gaming FPS or benchmarking results. In this respect it offered an increase in my 3DMark 11 results of close to 300 point at the performance preset. Dual 8-pin power connections show that a 375 watt draw is possible when you take into account the 75W coming from the PCIe slot. Minimum power supply requirements for using this card is a 500 watt power supply with an 850 watt PSU suggested for CrosfireX configurations.




Peeling off the heat sink and back plate allow us to get a closer look at what makes up the Sapphire HD 7970 6GB Vapor-X Edition. As large as the vapor chamber and heat pipe based cooler is, it is held on by only the four screws around the GPU core socket. The back plate is held on with more screws as it is used to provide structural rigidity for the PCB, as well as doubling as the heat sink for the back half of the power circuit and the 3GB of GDDR5 memory on the back. Just like the Toxic Edition, the PCB shows as jet black under a flash instead of a dark brown providing some visual appeal. Along the top of the PCB are a series of voltage check points that can be used when the blue cover over them has been removed and provide a useful access point for monitoring leads.




Sapphire uses its Blue Power+ 8+1+1 power circuit that includes an 8+1+1 phase power circuit running through a 12 layer PCB. Eight phases feed power to the CPU core with another dedicated to the memory and MVDD circuit. Used on both the Toxic Edition and the 6GB Vapor-X Edition are new double sided Black Diamond chokes and DirectFET technology that work to reduce operating temperatures of this part of the system by as much as 40 °C. Additional cooling comes by way of small heat sinks attached to the PCB. These cover the power circuits and are cooled from the airflow through the heat sink to keep the thermals in check. A CHIL CHL8228 controller is used to provide software based voltage control and monitoring.



As the main feature of this card the cooling solution bears a large percentage of the focus. Sapphire has put together a dual 90mm fan equipped vapor chamber design that uses four heat pipes (two 8mm in size and two at 6mm) to carry the thermal load from the vapor chamber plate to the aluminum fin array. An industrial looking shroud is mounted over the heat sink assembly for both looks and functionality. This new Vapor-X vapor chamber is designed specifically for this current generation of Vapor-X-equipped cards. The vapor chamber uses a stepped surface to mate with the core due to the shim used around the core. As seen on the Toxic and 3GB Vapor-X, a pair of small aluminum sinks are used to cool the power circuits and fit under the main thermal solution.



A pair of 90mm fans are used to drive the airflow through the thermal solution on this Vapor-X-equipped HD 7970 . Made by FirstD these fans are 90mm in size, PWM controlled, and feature an aerofoil fin design and hubs that are designed to be dust resistant, improving longevity of both the fans and the card. When run at maximum speed these fans are audible in the case. As fan speed is reduced the noise generated decreases to a point where the card is inaudible. While PWM controlled, the fans were incredibly quiet in comparison to a reference design.



AMD's GHz edition 28nm Tahiti core is just an improved process core that features the same GCN architecture and specifications as the non GHz edition parts with the exception of the Dynamic boost feature for the GPU core. Transistor count is 4.31 billion, stream processor count is 2048, texture units at 128, and ROPs at 32. GDDR5 memory is used on the HD 7970 6GB Vapor-X Edition and runs through a 384-bit bus. Hynix is the supplier of choice with its 1500MHz rated H5GQ2H24AFR-R0C modules, 24 of which are used to make up the 6GB frame buffer size on this 6GB-equipped card. The GHz Edition core is rated to run at 1000MHz with a dynamic boost clock of 1050MHz. Sapphire's EZ OC button adds 50MHz to the base clock to 1050MHz with a dynamic boost clock of 1100MHz with the push of a button. Memory speeds are left untouched at 1500MHz (6000MHz Effective) when in EZ OC mode.



Solidly built and equipped with the best Sapphire has to offer in terms of component selection and build quality, the HD 7970 6GB Vapor-X Edition should provide a challenge for the further upscaled Toxic edition. Let's see how it compares to the competition.



2 x Dual-Link DVI
1 x HDMI (with 3D)
2 x Mini-DisplayPort
1050MHz Core Clock
28 nm Chip
2048 x Stream Processors
6144 MB Size
384-bit GDDR5
6000 MHz Effective
275(L) x 115(W) x 42(H) mm
Driver CD
CrossFire™ Bridge Interconnect Cable
DVI to VGA Adapter
8 PIN to 2x4 PIN Power Cable x 2
Mini-DP to DVI active adapter
HDMI 1.4a high speed 1.8 meter cable





All information provided Courtesy of Sapphire @


Testing of the Sapphire HD 7970 6GB Vapor-X GHz Edition will consist of running it and comparison cards through the suite of games and synthetic benchmarks. This will test the performance against many popular competitors. Comparisons will be made to cards of a range of capabilities to show where each card falls on the performance ladder. The games used are some of today's newest and most popular titles, which should be able to provide an idea of how the cards perform relative to each other.

The system specifications will remain the same throughout the testing. No adjustment will be made to the respective control panels during the testing, with the exception of the 3DMark 11 testing, where PhysX will be disabled in the NVIDIA Control Panel, if applicable. I will first test the cards at stock speeds, and then overclocked to see the effects of an increase in clock speed. The cards will be placed in order from highest to lowest performance in each graph to show where they fall by comparison. The NVIDIA comparison cards will be using the 306.32 drivers with AMD cards using the Catalyst 12.8 drivers and latest CAP profile.


Testing Setup:


Comparison Video Cards:




Going into the testing I was looking forward to overclocking this card to the levels of the HD 7970 6GB Toxic Edition achieved with a core clock speed of 1235MHz and 1735MHz on the GDDR5 memory. This is where we find the difference in how well the Vapor-X edition and the Toxic edition vary and that is in the binning of the GPU cores. The first order of business was cranking the fan speed up to 100% for the best possible outcome. Cranking up the voltage seems to help in most cases but the last two cards I have worked with have shown no benefit to performance at an applied voltage any higher than 1185mv. This card was no exception and to keep the thermals in an even better spot I left the voltage at this level to find the highest stable clock speeds. 1205MHz on the core was stable in some of the games, but it would not pass in three of the seven tested so the maximum clock speed was reduced 5MHz at a time until it would pass all of the tests. 1175MHz on the core is where every test would pass repeatedly and Heaven 3.0 would run as long as it was open.

I started the memory testing after finding the core maximum and started at 1600MHz. I reached the maximum memory clock at 1661MHz fairly quickly. Again the memory could be run higher depending on the benchmark but passing all of the tests is the requirement for a successful overclock. The final clock speeds of 1175MHz on the core and 1661MHz on the memory are not world beaters but will add a nice boost to the level of performance you get when looking for that last FPS.

A feature of the HD 7970 6GB Vapor-X is the EZ OC button that allows the user to enable a quick and easy 50MHz boost above the level of the standard boost clock speed of 1050MHz to 1100MHz. Using this feature is a simple as shutting down the system, pushing the EZ OC button, then starting up the system and enjoying the fruits of your er...ah...labor! Using this button gave the card a solid 300+ point boost in the 3DMark 11 performance test.

Running a card overclocked and overvolted usually means a rise in temperatures. Running the fan at 100% when overclocked, the HD 7970 6GB Vapor-X delivered load temperatures of only 57 °C. At stock speeds with the card controlling the fan speed 66 °C was the result at an almost zero noise level. Putting that in perspective as each and every room is going to offer different acoustics, my zero noise level is if I can or cannot hear the fan running in the chassis. In this respect the auto settings on the fan controls deliver a card that runs quiet enough to hear the rest of the components in my chassis while delivering temperatures much better than a reference design cooler. 



Maximum Clock Speeds:

Testing for the maximum clock speed consists of looping Unigine 3.0 for 30 minutes each to see where the clock speeds fail when pushed. If the clock speed adjustment fails, then the clock speeds and tests are rerun until they pass a full hour of testing.



  1. Metro 2033
  2. Batman: Arkham City
  3. Battlefield 3
  4. Unigine Heaven Benchmark 3.0
  5. Sid Meier's Civilization V
  6. DiRT 3
  7. Mafia II
  8. 3DMark 11


  1. Temperatures
  2. Power Consumption


Part first-person shooter, part survival horror, Metro 2033 is based on the novel of the same name, written by Russian author Dmitry Glukhovsky. You play as Artyom in a post-apocalyptic Moscow, where you'll spend most of your time traversing the metro system, with occasional trips to the surface. Despite the dark atmosphere and bleak future for mankind, the visuals are anything but bleak. Powered by the 4A Engine, with support for DirectX 11, NVIDIA PhysX, and NVIDIA 3D Vision, the tunnels are extremely varied – in your travels, you'll come across human outposts, bandit settlements, and even half-eaten corpses. Ensuring you feel all the tension, there is no map and no health meter. Get lost without enough gas mask filters and adrenaline shots and you may soon wind up as one of those half-eaten corpses, chewed up by some horrifying manner of irradiated beast that hides in the shadows just waiting for some hapless soul to wander by.














In Metro 2033, the HD 7970 6GB Vapor-X Edition is the faster card at stock speed with a measurable margin over the reference card and GTX 680. When overclocked the higher speed attained by the comparison HD 7970 accounts for the higher results.


Batman: Arkham City is the sequel to Batman: Arkham Asylum released in 2009. This action adventure game based on DC Comics' Batman super hero was developed by Rocksteady Studios and published by Warner Bros. Interactive Entertainment. Batman: Arkham City uses the Unreal 3 engine.

















Again in this game the Vapor-X HD 7970 delivers higher levels of performance at stock speeds. At 1920x1080 the margin is only one FPS against the 1000MHz core clocked comparison card. The margin increases to two FPS at 5760x1080. When overclocked the Vapor-X shows nice gains in performance.


Battlefield 3 is a first-person shooter video game developed by EA Digital Illusions CE and published by Electronic Arts. Battlefield 3 uses the Frostbyte 2 game engine and is the direct successor to Battlefield 2. Released in North America on October 25, 2011, the game supports DirectX 10 and 11.

















In BF3 the HD 7970 6GB Vapor-X is three FPS faster than the Black Edition at 1920x1080 and three FPS slower than the GTX 680. At 5760x1080 the scoring is a dead heat between the HD 7970s.


Unigine Heaven Benchmark 3.0 is a DirectX 11 GPU benchmark based on the Unigine engine. This was the first DX 11 benchmark to allow testing of DX 11 features. What sets the Heaven Benchmark apart is the addition of hardware tessellation, available in three modes – Moderate, Normal and Extreme. Although tessellation requires a video card with DirectX 11 support and Windows Vista/7, the Heaven Benchmark also supports DirectX 9, DirectX 10, DirectX 11 and OpenGL 4.0. Visually, it features beautiful floating islands that contain a tiny village and extremely detailed architecture.
















At 1920x1080 and 5760x1080, again the Sapphire HD 7970 6GB is the higher performing HD 7970 when clock speeds are similar. Overclocking again shows higher clock speeds to be an advantage between the HD 7970 cards.


Civilization V is a turn-based strategy game. The premise is to play as one of 18 civilizations and lead the civilization from the "dawn of man" up to the space age. This latest iteration of the Civilization series uses a new game engine and massive changes to the way the AI is used throughout the game. Civilization V is developed by Firaxis Games and is published by 2K games and was released for Windows in September of 2010. Testing will be done using actual game play with FPS measured by Fraps through a series of five turns, 150 turns into the game.

















The Sapphire HD 7970 6GB Vapor-X is clearly the fastest of the comparison cards at stock speeds. Even with a lower overclock sit still delivers performance above that of the GTX 680.


DiRT 3 is the third iteration of this series. Published and developed by Codemasters, this game uses the EGO 2.0 game engine and was released in the US on PC in May of 2011.

















Again the performance results charts look almost identical to the rest of the games in this test with the HD 7970 6GB Vapor-X showing a margin over the 1000MHz core clock comparison HD 7970 while offering the highest level of performance at stock speeds.


Mafia II is a third-person shooter that puts you into the shoes of a poor, Sicilian immigrant, Vito Scarletta. Vito has just returned home from serving overseas in the liberation of fascist Italy, to avoiding his jail sentence, to finding his family in debt. The debt must be repaid by the end of the week, and his childhood friend, Joe Barbaro, conveniently happens to have questionable connections that he assures will help Vito clear the debt by that time. As such, Vito is sucked into a world of quick cash. Released in North America for PC in August of 2010, the game was developed by 2K Czech, published by 2K, and uses the Illusion 1.3 game engine.














In Mafia II the GTX 680 is faster than the HD 7970 6GB Vapor-X by a very small margin.


3DMark 11 is the next installment in Futuremark’s 3DMark series, with Vantage as its predecessor. The name implies that this benchmark is for Microsoft DirectX 11 and with an unintended coincidence, the name matches the year proceeding its release (which was the naming scheme to some prior versions of 3DMark nonetheless). 3DMark 11 is designed solely for DirectX 11, so Windows Vista or 7 are required along with a DirectX 11 graphics card in order to run this test. The Basic Edition has unlimited free tests on performance mode, whereas Vantage is only allowed for a single test run. The advanced edition costs $19.95 and unlocks nearly all of the features of the benchmark, while the professional edition runs $995.00 and is mainly suited for corporate use. The new benchmark contains six tests, four of which are aimed only at graphical testing; one to test for physics handling and one to combine graphics and physics testing together. The open source Bullet Physics library is used for physics simulation and although not as mainstream as Havok or PhysX, it still seems to be a popular choice.

With the new benchmark, comes two new demos that can be watched, both based on the tests. Unlike the tests, however, these contain basic audio. The first demo is titled "Deep Sea" and involves a few vessels exploring what looks to be a sunken U-Boat. The second demo is titled "High Temple" and presents a location similar to South American tribal ruins with statues and the occasional vehicle around. The demos are simple in that they have no story – they are really just a demonstration of what the testing will be like. The vehicles have the logos of the sponsors MSI and Antec on their sides – the sponsorships helping to make the basic edition free. The four graphics tests are slight variants of the demos. I will use the three benchmark test preset levels to test the performance of each card. The presets are used as they are comparable to what can be run with the free version, so that results can be compared across more than just a custom set of test parameters.












In 3DMark 11 the HD 7970 Vapor-X offers up excellent results for the clock speeds it has. In all three of the stock tests the card is just slower than the GTX 680.


Temperature testing will be accomplished by loading the video card to 100% using Unigine's Heaven Benchmark Version 3.0, with MSI's Afterburner overclocking utility for temperature monitoring. I will be using a resolution of 1920x1200 using 8xAA and a five-run sequence to run the test, ensuring that the maximum thermal threshold is reached. The fan speed will be left in the control of the driver package and video card's BIOS for the stock load test, with the fan moved to 100% to see the best possible cooling scenario for the overclocked load test. The idle test will involve a 20-minute cool-down, with the fan speeds left on automatic in the stock speed testing and bumped up to 100% when running overclocked.














Sapphire's Vapor-X cooling solution pays off when it comes to the temperatures delivered by this card. Under load at both stock and overclocked it is cooler than the reference cooled XFX Black Edition. The overclocked temperature difference between the two is only three degrees when overclocked, but the noise difference is where the biggest bang for the buck occurs with the Vapor-X running much quieter when the fan speeds are ramped up to 100%.

While the overclocked results are seemingly not that impressive as far as temperatures are concerned, the difference when running at stock speeds with vBIOS-controlled fan settings is very much so. The Vapor-X cooling delivers a 12 degree improvement over the reference cooling solution on the reference cooled HD 7970.


Power consumption of the system will be measured at both idle and loaded states, taking into account the peak voltage of the system with each video card installed. I will use Unigine's Heaven Benchmark version 2.5 to put a load onto the GPU using the settings below. A 15-minute load test will be used to heat up the GPU, with the highest measured temperature recorded as the result. The idle results will be measured after 15 minutes of inactivity on the system. With dual-GPU setups, the two core temperatures will be averaged.














In three out of four scenarios the Sapphire HD 7970 6GB Vapor-X is more efficient than the reference design thanks to its custom ten phase power design, Black Diamond chokes, DirectFET technology and 12 layer PCB.


Sapphire's Vapor-X cooling solutions have been at the forefront of cooling its top end video cards since the introduction of the HD 3870 Atomic Edition, seen first at OCC back in 2008. The follow up cards over the years have been no less spectacular with the ability to cool both the mid and high range with innovative vapor chamber-based cooling solutions. That being said, the design used on the HD 7970 6GB Vapor-X is equipped with four heat pipes that connect the vapor chamber to the aluminum fin array and uses a pair of 90mm aerofoil fans. These fans are designed with multiple seals that reduce dust intrusion into the motors to allow the fans to run at their rated speeds long term without fear of a dust related fan failure cooking the TahitiXT core during a marathon frag fest.

By using dual fans, the speed of these fans do not need to ramp up to stratospheric levels to achieve the cooling goals of the Vapor-X cooling solution. Testing shows that when the fan speeds are ramped to 100% the reference solution puts up decent thermal performance numbers when compared to the Vapor-X design on this card but comes with a pretty significant noise penalty. The Vapor-X cooler is not silent when ramped up but is significantly quieter. Now where you really see the Vapor-X HD 7970 6GB strut is when you compare the thermal performance numbers at stock speeds where the Vapor-X cooler allows the GPU core to run 12 °C cooler with no noise heard outside of the chassis. An excellent cooling solution is not all this card is about. Coupled with the cooling is a custom, black, 12 layer PCB equipped with Sapphire's Vapor-X Dynamic Power suite. Features include not only the 12 layer PCB but a ten phase power circuit using DirectFET technology, solid capacitors, and Sapphire's own Black Diamond chokes seen on many of its high end products from video cards to motherboards. Basically just about all of the feature set of the HD 7970 Toxic Edition for less cost.

The Vapor-X cooling solution does allow for increased overclocking margins to a point where the core is only going to give up what it can. Voltage tuning helps, but you reach a point where voltage no longer helps drive a core clock speed increase. This particular HD 7970 6GB Vapor-X GHz Edition sample was able to reach in excess of 1200MHz on the core and 1700MHz+ in some tests but would fail at others. The final clock speeds of 1175MHz on the core and 1661MHz are the levels that would pass all of the test suite along with a series of gaming sessions without failing. The core speed increases of just over 17% on the core and just over 11% on the 6GB of GDDR5 memory are enough to drive measurable performance increases.

To reach these levels, Sapphire has its own tweaking utility called TriXX; a simple to use and functional utility that enables the end user to tune the performance of the HD 7970 6GB Vapor-X. If manually tuning the card is not your style you can get in on the simplest overclock out there right now with a feature of the HD 7970 6GB Vapor-X GHz Edition called the EZ OC button. This button enables a boost on the GPU core clock of 50MHz to 1050MHz with a dynamic boost clock of up to 1100MHz. This button tunes the fan profile, voltage, and clock speed to deliver a higher level of performance.

Performance numbers when compared to the 1000MHz clocked reference design show that the addition of 3GB to the frame buffer along with the Power Tune Dynamic Boost has some advantages. Unfortunately clock speed cures this discrepancy in just about all of the tests I ran where a 3GB-equipped card was able to out perform the 6GB-equipped Vapor-X even in an Eyefinity configuration at 5760x1080. That being said the vast majority of users will use this card right out of the box and push the EZ OC button to kick the clock speeds up without any other tuning. In this respect you get a higher level of performance by comparison. In content creation or video editing scenarios where GPU boosted performance can help reduce the length of time the workload runs, additional video memory can prove beneficial.

At $599 the cost upswing of around $150 over a similarly equipped Vapor-X 3GB card is going to be a deal breaker for the average user looking for a Sapphire HD 7970. Unless running a three to six monitor Eyefinity configuration, the benefits in memory capacity is not really worth the up charge. However the gains in power efficiency under load due to the Vapor-X Dynamic Power suite design power circuit allows the end user to gain some of that up charge back over time. As part of Sapphire's Vapor-X Lineup the HD 7970 6GB Vapor-X GHz edition video card can play anything you can throw at it with the eye candy turned up. It offers excellent cooling and noise characteristics to go along with Sapphire's top end build quality.