PowerColor Devil 13 HD 7990 Reviewccokeman - September 16, 2012
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The first glance of the Devil 13 is impressive. The card is absolutely massive for a video card, measuring just over twelve inches in length, just over five inches high, and just over two inches from front to back. The front view shows the three fans that are used to provide airflow over the large copper and aluminum heat pipe cooling solution. A pair of 92mm and a single 80mm fans are used in this configuration. The fans are circled in red as part of the design element of the card and fit well with the black PCB. The shroud is made from aluminum and is fairly robust. The back side of the card has a back plate with the Devil 13 logo in the center as an identifier so that you can show off the card through your chassis window. The back plate serves two purposes: to act as a brace to keep the PCB from bending and to help dissipate the thermal load from the memory on the back of the PCB. Viewing the bottom and top of the Devil 13 it looks like PowerColor has managed to keep all ten of the U-shaped heat pipes inside the shroud for a clean look. When you compare this card to the GTX 690 the actual size of it is clearly evident as the GTX 690 is no slouch in the size department.
Visible through the cutouts in the back plate are a series of LEDs that provide a visual indication of how heavily loaded each of the Tahiti XT cores are loaded. One strip covers the back GPU and and one the front. The enthusiast is thought of with this card as PowerColor provided a series of voltage check points on the PCB right in front of the forward most 8-pin PCIe connection. You can check voltages from the front and back side of the PCB.
Connectivity options on the Devil 13 are not quite standard for the HD 79XX series cards from AMD. Included are both a Single Link DVI and Dual Link DVI output, a single HDMI 1.4a output that supports Dolby® TrueHD and DTS-HD Master Audio, and a pair of Mini Display port 1.2 connections that support daisy chaining and the use of an MST hub to support Eyefinity configurations of up to six monitors. Eyefinity 2.0 brings along added functionality with independent audio streams for each video stream, allowing that audio stream to follow the video to each specific monitor. The big red button in the middle of the I/O bracket is connected to the PCB and functions as a dual BIOS switch changing the core clock from 925MHz to 1000MHz. The memory clock speed is unchanged at 1375MHz. Airflow out of the chassis is managed with the rest of the available space used as a vent for the thermal load. The back end of the Devil 13 is vented to allow airflow out of the shroud. The fan connection is at the bottom of the back end of the PCB and leads to all three fans.
Along the top of the PCB are additional connections that include the single CrossfireX bridge connection, which allows a connection to another HD 7990 or HD 7970 for four or three-way CrossfireX configurations. The power needs for this card are significant with three 150 watt 8-pin PCIe power connections required to deliver the current needs for this card. The minimum power supply requirement comes in at a hefty 850 watts. That's just the minimum requirement so the optimum solution will be rated higher.
The massive cooling solution comes in several parts: the shroud, the three fans, the ten heat pipe-based cooler, and a back plate that adds stability as well as cooling for the GDDR5 memory on the back of the black PCB. The heat sink sits above most of the board when installed so the VRM component heat sinks and memory on the front side of the PCB only get airflow through the cooler as the only means of temperature control. The heat sink's base is a large copper plate that has a pedestal that contacts the Tahiti XT cores. There are a total of ten 6mm copper heat pipes that are employed to move the thermal load from the GPU cores and copper base to the aluminum fins to be carried away by airflow from the three PWM controlled fans. This cooling solution design as it sits is rated to disperse 550 watts of thermal energy.
The fan layout on the Devil 13 is as unconventional as the rest of the video card with a pair of 92mm fans flanking a single 80mm fan handling the airflow requirements of the cooling solution. The ability to remove 550 watts of thermal energy means that airflow is crucial to the survival of the card and the three fans from ApisteK seem to do the job. Little information is available on these fans but they are PWM controlled and run on 12vdc -.46a. Three fans singing at full song are going to be loud; surprisingly though a pair of reference cooled HD 7970s at 100% fan speed is much louder than the Devil 13 HD 7990. The fans excel at the job of cooing this beast down to the tune of a 72 °C average under load at stock speeds. The delta between the cores is right at 5 °C with the back core running warmer, most likely due to being in close proximity to the 12+2+2 VRM circuit.
Pulled apart so that the PCB is laid bare you can get a good glimpse of the PCB layout. The back end of the PCB has the digital 12+2+2 power circuit that uses PowIRstage chokes and "Super" Capacitors as labeled on the cards breakdown. The MOSFETs are covered with extruded aluminum heat sinks. The heat sink in between the cores is over a PLX bridge chip to provide 16 PCIe lanes for each GPU core to the PCIe bus. The dual BIOS button is connected to the PCB by a short wire harness plugged in just above a part of the VRM package.
At the heart of the Devil 13 HD 7990 are a pair of AMD's 28nm Tahiti XT cores and 2 x 3GB of GDDR5 memory on dual 384-bit bus. Each of the GCN architecture cores has a transistor count of 4.31 billion, stream processor count at 2048, texture unit count of 128, and the ROP count of 32 just like on every HD 7970 core on the market. On the Devil 13, GDDR5 memory is used with a total of 6GB on board running through a pair of 384-bit buses. Hynix GDDR5 part number H5GQ2H24MFR-R0C rated at 1500MHz is used on the Devil 13 HD 7990. Rated clock speeds from the factory are 925MHz on the GCN core and 1375MHz on the memory. A Boost clock is available at the touch of a button to increase the core speed to 1000MHz for improved performance in games. A Chil CHL8228 digital controller is used to enable software monitoring and voltage control on the Devil 13 HD 7990. A pair of these are used, one for each GPU core.
As the first to make the leap to designing a custom card it looks like PowerColor had its work cut out. Running at the default clock speeds it should match up well with the GTX 690. But with three 8-pin PCIe power connections the power consumed may well be higher. On just looks and size alone this card is a beast, so let's see if the performance can match the looks and packaging.