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PCB Design

The XFX R7970 Double Dissipation Edition is obviously different from the reference AMD Radeon HD 7970. The silvery casing of its dual-fan cooler and the bright-red piece on its side make it attractive, but not gaudy.

The back side of the PCB is open, just like with the reference Radeon HD 7970, so you should be careful when handling it. The device measures 270 x 100 x 38 millimeters.

Like the reference sample, the card offers one dual-link DVI-I, one HDMI version 1.4a, and two DisplayPorts version 1.2.

The XFX-shaped vent grid makes the card’s identity easily recognizable.

Like the reference sample, the XFX card has 8- and 6-pin power connectors, two MIO connectors for CrossFireX configurations and a BIOS switch.

 

The peak power consumption of the Radeon HD 7970 is 250 watts in 3D mode. It is 70 watts in 2D mode and 3 watts when the monitor is turned off.

The XFX R7970 Double Dissipation Edition uses the reference PCB we examined in our first Radeon HD 7970 review.

Like the reference Radeon HD 7970, the XFX card is equipped with a 5+1 power system based on DirectFETs with five phases for the GPU and one phase for the memory chips.

The power system is managed by a CHiL CHL8228G controller which lacks a heatsink and is not even cooled by air flow on the XFX card.

The previous tester took the protective frame of the 28nm GPU off and forgot to glue it back on.

The GPU looks so exposed without it. The GPU configuration is standard for a Radeon HD 7970: 2048 unified shader processors, 32 raster operators and 128 texture-mapping units. As opposed to other XFX products, the R7970 Double Dissipation Edition has the same clock rate as the reference card: 925 MHz at 1.112 volts in 3D mode and 300 MHz at 0.85 volts in 2D mode. The XFX card has a lower voltage than the reference Radeon HD 7970 we tested earlier.

The XFX R7970 Double Dissipation Edition is equipped with 3 gigabytes of GDDR5 memory in 12 FCFBGA-packaged chips located on the face side of the PCB. Manufactured by Hynix Semiconductor, the chips are labeled H5GQ2H24MFR R0C:

They have a frequency of 5500 MHz at a voltage of 1.6 volts in 3D mode. The memory bus being 384 bits wide, this means a bandwidth of 264 GB/s. The memory clock rate is lowered to 600 MHz in 2D mode.

Thus, the XFX R7970 Double Dissipation Edition has the same specs as the reference AMD Radeon HD 7970:

The ASIC Quality screenshot on the right can be evoked from GPU-Z's context menu and is individual for each graphics card and GPU. This feature has been developed for Nvidia’s Fermi (GX10x and GF11x) and AMD’s Southern Islands chips (Radeon HD 78xx and HD 79xx) and is supposed to indicate the quality of the specific GPU, in percent, based on electrical leakage data. The GPU of our sample of the card has an ASIC quality of 76.6%. The higher this number, the lower voltage the GPU needs to work at the default clock rate and the higher overclocking results you can get with it by increasing its voltage.

According to Alexey Nikolaichuk (the author of RivaTuner and MSI Afterburner), the correlation between voltage and quality is like follows:

ASIC quality < 75% - 1.1750 V;
ASIC quality < 80% - 1.1125 V;
ASIC quality < 85% - 1.0500 V;
ASIC quality < 90% - 1.0250 V;
ASIC quality ≤ 100% - 1.0250 V.

The GPU of our sample of the XFX card matches this correlation well enough.

 
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