AMD Radeon HD 6950 & 6970 CrossFire Video Card Reviews

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Radeon 6970 & 6950 GPU Overclocking

AMD Catalyst Overdrive PowerTune

To overclock the AMD Radeon HD 6900 graphics cards series, we used the ATI
Overdrive utility that is part of the CATALYST Control Center. When you
‘unlock’ the ATI Overdrive, you can manually set the clock and memory
settings or let the ‘auto-tune’ utility set the frequencies for you. Well, that is what you used to be able to do.  It appears that when AMD added the ‘power control settings’ for PowerTune they did away with the ‘auto-tune’ that we have used for years to automatically overclock our video cards!

“Our design team decided to replace the Auto Tune test and put the PowerTune Power Control slider in its position in the interface.” - AMD PR

We then asked AMD if increasing the power control settings would help overclocking and they responded with this statement.

“Overclocking will presumably cause most apps to draw more power, which means some of the more stressful ones may spend more time being constrained by the PowerTune limit and having their clock frequency throttled. Increasing the PowerTune limit should provide more opportunity for performance increases in those cases, but it shouldn’t otherwise affect the maximum achievable clock speed.” - AMD PR

The short answer is that if you are overclocking you are likely not going to care about energy efficiency, so go ahead and max out the power control settings so AMD PowerTune doesn’t rob any performance from your game play.

AMD Radeon HD 6950 Video Card Overclock

The AMD Radeon HD 6950 starts off life at 800MHz on the core and 1250MHz on the memory.  We were able to max out AMD Overdrive at 850MHz core and 1325MHz on the memory and didn’t see any issues in the games with PowerTune left alone. This is a 50MHz overclock
on the core and a 75MHz boost on the 2GB worth of GDDR5 memory ICs. Not a huge overclock by any means, but we expect to see a difference in the benchmarks.

To test out the overclock we fired up 3DMark Vantage to see what this overclock was like. 

The AMD Radeon HD 6950 Video Card Stock 800MHz/1250MHz:

AMD Radeon HD 6950 OC Video Card Overclocking

The AMD Radeon HD 6950 Video Card Overclocked 850MHz/1325MHz:

ATI Radeon HD 6950 OC Video Card Overclocking

Running 3DMark Vantage with the Extreme preset we got a
score of X9393 with the card at reference clock settings.  The score went up X9873 3DMarks when overclocked, which
was an improvement of 480 points or 5% with this mild overclock. Let’s see how the AMD Radeon HD 6970 overclocked using the same methods.

AMD Radeon HD 6970 Video Card Overclocking

The AMD Radeon HD 6970 comes with an 880MHz core clock and 1375MHz
memory clock.  We were able to manually crack the clock frequencies up to the highest setting allowed in CCC and were able to reach 950MHz on the core clock and 1450MHz on
the memory. This is a 70MHz overclock on the core and a 75MHz boost on
the GDDR5 memory ICs. 

The AMD Radeon HD 6970 Video Card Stock 880MHz/1375MHz:

AMD Radeon HD 6970 OC Video Card Overclocking

The AMD Radeon HD 6970 Video Card Overclocked 950MHz/1450MHz:

ATI Radeon HD 6970 OC Video Card Overclocking

Running 3DMark Vantage with the Extreme preset we got a
score of X10837 with the card at stock settings.  The score went up X11573 3DMarks when overclocked, which
was an improvement of 736 points or 7% with this easy to do overclocking method.
Seeing a nice 5-7% performance gain with pretty much zero effort was
nice to see and if we had more time and a 3rd party overclocking tool we are sure these cards could be
pushed even harder!

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