AMD Radeon HD 7970 GHz Edition Video Card Review



Product: AMD Radeon HD 7970 GHz Edition
Company: AMD
Author: James Prior
Editor: Charles Oliver
Date: June 21st, 2012

Overclocking, Power, Temps

Disappointingly, AMD hasn't changed to a new reference cooler design; we still have the blower fan vapor chamber design. This isn't a bad design by any means, but it's not what enthusiasts want - dual or triple axial fans on a direct contact heatpipe design heatsink, with memory chip cooling is the desire, but AMD's partners will deliver that.

Overclocking is a little different from before, as the new Boost mode changes how the driver works. AMD hasn't yet spread the word to third party vendors on how to use the new libraries yet, causing some consternation as now all the 3rd party overclocking tools don't work. Given how ASUS, Sapphire, HIS and MSI all differentiate their products with on-the-box promises of overclocking ability (including voltage control) this surely won't last long, but it does mean initial overclocking is hampered.

The overclocking limits in the Vision Engine Control Center (or Catalyst Control Center, if you're running a non-AMD CPU ... which is more likely if you are using a 7900 series) are higher than on previous 7970s, and the adjustment affects only the Boost (also known as High Performance) clock. You can't disable Boost, for no good reason we can understand, but during our briefing and Tahiti half birthday party at AFDS '12 we learned that the PowerTune limits should never prevent Boost from fully activating unless you're running Power Viruses, or adjusting voltage. Which you can't do yet, anyway.

  7970 GHz Ed 7970 G.E. O/C  
Engine Clock 1050MHz 1130MHz +7.6%
Memory Speed 1500MHz / 5.5Gbps QDR 1650MHz / 6.6Gbps QDR +10%

As previously noted, the base full screen 3D clocks of the Tahiti XT2 are 1GHz, up from the 925 of the first edition. Memory clock is also bumped, hitting a full 6Gbps / 1500MHz, a nice bump from the 1375MHz / 5.5Gbps of the original. In our testing we could hit 1130MHz on the engine and 1650Mhz / 6.6Gbps on the memory, which was quite disappointing - ~7.5% increase in engine clock and 10% increase in memory clock. While our reference first edition Tahiti card couldn't match those clocks, we've got 3rd party tools that let us tweak it to exceed it easily; but only when the GHz Edition isn't present.

Power

Crossfire Power and Temps

For Crossfire we ran both cards at their default, unmatched, speeds.

Using identical coolers the 7970s have the same noise profiles, although the new XT2 appears to run a little cooler than our original XT sample, but not enough to be further down the reference fan profile ramp. Looking at the ASIC quality in GPUz of our samples we see our original XT is rated around 67% and the new XT2 at 74%. Different quality ASICs may be cooler and thus less noisy, but you're still best off getting a custom AIB model with a dual or triple fan cooler instead of this one.