Value and Conclusion

AMD's new PowerTune Boost is following in NVIDIA's steps by evaluating a graphics card's power consumption more closely to provide an additional speed boost. While NVIDIA's system works its way "up", increasing the clocks beyond the default clock when possible, AMD's system works its way "down." By default, the card runs at a higher clock speed, 925 MHz in this case, and, when the card senses that it exceeds the power limit, or is close to, the GPU will be clocked down to make sure power consumption stays within defined parameters.

Unlike NVIDIA's system, AMD does not use any power monitoring hardware. Instead, an algorithm (running purely in the GPU), evaluates internal GPU performance counters to estimate power draw. This has the advantage that every card performs the same, no matter random production variances. It also helps keep board cost down since no additional circuits are needed.

In the case of the Radeon HD 7950 Boost, AMD has increased clock speeds from 800 MHz on the original reference design to up to 925 MHz - as long as the card doesn't exceed its power limit. Averaged over all our benchmarks, this can result in a 5% real life performance increase - certainly a welcome improvement considering that NVIDIA's GTX 660 Ti is just around the corner.

However, I do not agree with AMD's methods to achieve the performance boost. We measured an increased GPU voltage from 1.07 V on the original design, to 1.12 V on the HD 7950 Boost. Increased voltage will lead to increased stability at higher clock speeds, which is probably required to ensure that all cards can handle the increased clocks. This, unfortunately, means that power consumption is increased by around 20% during typical gaming, which seems to be a bad trade for a 5% performance improvement. I am a bit worried that AMD is cannibalizing on the hard work of their GPU development team to reduce power consumption - we've seen the same on the HD 7970 GHz Edition. The HD 7950 Boost has, as a result, 15% worse performance per Watt compared to the original HD 7950 design. This, considering that NVIDIA has taken a leadership position in performance per Watt now, seems to be the wrong direction to take.

According to AMD, we will see the new Boost algorithm implemented on all newly produced HD 7950 cards - many board partners are also working on new designs to properly market this change. AMD promises that the higher clock speeds will come at no cost for the end user which is something I applaud the company for. The new BIOS also increases Catalyst Control Center Overdrive limits by 100 MHz to 1200/1575, great for users who don't want to install additional overclocking software.

Experienced users, who already have a HD 7950 reference design, can also download the BIOS and flash it, removing the need for any additional investment. AMD's dual-BIOS feature makes this a foolproof task as it is easy to recover in case something goes wrong during the flashing process.