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Design and Functionality

The reference Radeon HD 7970 GHz Edition looks absolutely identical to the regular HD 7970.

It has the same dimensions: (278 x 100 x 38 millimeters) and the same selection of connectors including one dual-link DVI-I connector, one HDMI version 1.4a, and two DisplayPorts version 1.2:

And like its non-GHz cousin, the Radeon HD 7970 GHz Edition is equipped with 8- and 6-pin power connectors, two MIO connectors for building CrossFireX configurations, and a small switch to choose one of two BIOS versions.

 

Notwithstanding the increased clock rates, the new card is specified to have the same power draw as its predecessor: up to 250 watts in 3D mode. In 2D applications the Radeon HD 7970 GHz Edition may be as economical as 3 watts (when the monitor is turned off). If you have a CrossFireX configuration, every card, save for the master, is shut down in 2D applications, which is a useful power-saving feature of the entire Radeon HD 79xx series.

We could find no differences from the regular Radeon HD 7970 in terms of the PCB design and component layout, either.

Like the HD 7970, this card has a 5+1 power system with five phases for the GPU and one phase for the memory chips.

The power system is managed by a CHiL Semiconductor CHL8228G controller located at the back of the PCB.

Here is the 28nm GPU of our sample of the card:

As you may have already learned from the specs table, the GPU has no functional changes, incorporating 2048 unified shader processors, 32 raster back-ends, and 128 texture-mapping units. Its clock rate is increased from 925 to 1000 MHz while the new boost mode can accelerate the GPU up to 1050 MHz. Thus, the AMD Radeon HD 7970 GHz Edition can be said to have a 13.5% higher GPU clock rate than the ordinary Radeon HD 7970. According to our monitoring tools, the GPU voltage was 1.256 volts in 3D mode. In 2D applications, when the GPU clock rate is dropped to 300 MHz, the voltage was lowered to 0.949 volts.

The ASIC quality level of our GPU is very low at only 56.3%:

Like on a regular Radeon HD 7970, there are 3 gigabytes of GDDR5 memory in 12 chips (Hynix H5GQ2H24AFR R0C).

The chips are rated for a clock rate of 6000 MHz and that’s exactly the memory frequency of the reference Radeon HD 7970 GHz Edition as opposed to the Radeon HD 7970’s 5500 MHz (+9.1%). With the 384-bit bus, the memory bandwidth is a record-breaking 288 GB/s. The card drops its memory frequency to 600 MHz in 2D mode.

The AMD Radeon HD 7970 GHz Edition has no other differences from its non-GHz cousin:

 

 
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