Sapphire HD 7970 6GB Toxic Edition Reviewccokeman - July 16, 2012
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Sapphire's latest HD 7970, the 6GB Toxic Edition, is built upon the GHz Edition 28nm GCN "Tahiti" Core from AMD. Just by looks alone you can tell that this card is far from a reference design card from the black 12 layer PCB to the large dual fan equipped Vapor-X cooling solution and Lethal Power Suite VRM design. At 11 inches in length, the HD 7970 6GB Toxic Edition should not provide any fitment issues in most mid tower or larger cases. The 11 inch card hangs over the motherboard PCB by about 1/8th of an inch on a full size ATX form factor motherboard. From the top you can see that Sapphire implemented a dual fan custom cooling solution with the Toxic logo on each fan while the back side has the Vapor-X logo on the back plate used to dissipate the thermal load from the 3GB of memory on the back side of the PCB. The opening on the back is used to clear part of the Lethal Power Black Diamond chokes. The side views give a glimpse of the four heat pipe cooling solution and shroud. The Sapphire logo is lit with a white LED and is visible when the card is powered on and in operation. This card is built to work within the PCIe 3.0 specification with motherboards that support the specification.
Connectivity on the HD 7970 6GB Toxic Edition is much like what you would find on one of Sapphire's Flex Edition cards with a pair of Dual Link DVI ports, an HDMI 1.4a port and a pair of Mini DisplayPort 1.2 ports. By using an MST hub or daisy chaining DisplayPort monitors you can get up to six displays in an Eyefinity setup out of the pair of Mini DP ports. 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 it. Venting on the mounting bracket is compromised somewhat by the second DVI port but it looks like Sapphire opened up all possible avenues for airflow. The rear of the card is open to vent out the thermals from the card. Both of the fans used on the cooling solution are plugged into separate headers on the PCB.
Just like the rest of the HD 79XX series the Toxic Edition supports CrossfireX with up to four cards in a supporting motherboard using the dual bridge connections. Under the Crossfire bridge connections are a series of LEDs to monitor the temperature of the PCB and report in a visual fashion, Green-Yellow-Red, with the associated common meanings for the LEDs. Past versions of the HD 7970 used a dual BIOS switch to recover from a bad flash or to flash a different BIOS file with higher clock speeds. On the Toxic Edition Sapphire has come up with a different solution that takes away that recovery options but put that second file as the Lethal Boost file that increases the core clock and memory speeds, Power Tune settings and loads a fan profile to compensate for the higher clocks and voltage levels. When enabled the button turns blue to show the profile is enabled. On this card the clock speeds will see maximums of 1200MHz on the "Tahiti" core and 1600MHz on the 6GB of memory. This is a significant boost with just a button push. I found this button to work as advertised with a boost in 3DMark 11 performance of over 500 points using the performance preset. Dual 8-pin power connections are used to supply the current demands of the Toxic Edition HD 7970 with a 375 watt draw possible via the power connections and PCIe slot.
Pulling the card apart shows the custom layout and Lethal Power Suite power design. The cooling solution comes off with four screws while the back plate is held in place by many more. The heat sinks on the VRM circuits are held to the back plate for a much more secure mount than push pins can offer. The front of the PCB and back of the PCB have significant elements of the Lethal Power Suite 8+1+1 power circuits.
Sapphire uses an 8+1+1 power circuit called Lethal Power Suite 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 in this implementation 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. Under the small blue cover above the eight phase power circuit are what looks like a series of voltage check points that could prove useful for the extreme overclocker.
The cooling solution used on the Sapphire HD 7970 6GB Toxic Edition is a dual 90mm fan cooled vapor chamber and heat pipe-equipped solution. The shroud mounts over the heat sink assembly for easy removal. What Sapphire has put together is a new Vapor-X vapor chamber designed specifically for this card. The vapor chamber has a stepped surface to mate with the core due to the shim around the core. Four heat pipes in total pull the thermal load away form the vapor chamber and carry it to the fin array. Two of the heat pipes are 8mm in size with two at 6mm. A pair of small aluminum sinks cool the power circuits and fit under the main thermal solution.
Dual fans are used on the thermal solution on the Toxic Edition. These fans made by FirstD 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 the fans are audible in the case depending on the fan speed used. While PWM controlled they were incredibly quiet by contrast to a reference cooling solution.
Lastly we get to the GPU core and memory. The GHZ edition 28nm Tahiti core is just an improved process core that features the same GCN architecture and specifications for the most part. Transistor count stays at 4.31 billion, the stream processor count stays at 2048, texture units at 128, ROPs stay at 32. GDDR5 memory is used but the capacity on this card increases to 6GB from 3GB, but still running on a 384-bit bus. Where this core gets its performance chops is from the increase in base clock speeds on the core and memory. Sapphire bumped up the clock speeds from 1000/1050MHz on the reference GHz Edition card to 1050/1100MHz on the Toxic with a boost to 1150/1200MHz using the Lethal Boost feature. Twenty-four Hynix GDDR5 modules with part number H5GQ2H24AFR-R0C are used to make up the massive and industry first 6GB frame buffer and are rated to run at 1500MHz. With the Lethal Boost feature these easily run at 1600MHz. Software based voltage control is available with the use of the CHIL voltage controller.
Seeing how the card is built and all that has been done to improve on the basic design set of the reference card, the Sapphire HD 7970 6GB Toxic Edition is poised to sit atop the HD 7970 performance mountain and ready to play King of the Hill.