GeForce 8 Mobile - The Next Chapter in Notebook Graphics

Improved Power Efficiency

Improved Power Efficiency

The power efficiency of the various notebook components play a key role in prolong the life of a notebook and ever since Intel's Centrino Technology, consumers have had very high expectations in this department. Compared with its integrated graphics controller, a discrete GPU is a potential problem for the notebook vendor to maintain long batter life by virtue of the design and performance nature of the GPU component. Thankfully over the years, the graphics giants of the industry have been constantly improving their designs for greater efficiency while boosting performance in tandem. The new GeForce 8M series follows this principle too and as mentioned on the earlier page, these new GPUs are up to twice the performance of its predecessors while maintaining the same TDP envelope.

Windows Vista however, brings about new challenges as its fancy Aero interface requires constant use of a GPU's 3D pipeline, which in turn translates to more power consumption. To counter this concern as well as improve overall power efficiency of a notebook, NVIDIA has revised the PowerMizer to version 7.0 on the GeForce 8M series. This latest iteration of NVIDIA's power saving technology incorporates several enhancements that brings about both GPU and system-level power savings. Featuring improved power saving circuitry for the PLLs, TMDS controllers and PCIe bus, it ensures only the required power is used depending on the operating state of these components; but wait, there's more. Activity based switching between performance modes and Adaptive Clocking to dynamically tune power to match demand, as well as Dynamic Clock Gating to shut down unused circuitry all help to keep power consumption levels in check. So for example you are gaming away on your notebook, the GPU can shut down the PureVideo HD engine if there's no need for it.

The diagram illustrates the benefits of having a GeForce 8600/8400 series mobile GPU. As you can see, thanks to the additional bitstream processor, HD video decoding can now be fully offloaded to the graphics engine, where previously certain processes still needed the attention of the CPU.

Speaking of PureVideo HD, the new VP2 video processing engine drastically reduces CPU utilization for HD video playback and as shown in our GeForce 8600 GTS article, is extremely competent in handling heavy-duty tasks like playback of Blu-ray and HD DVD movies encoded in MPEG-2, VC-1 and even H.264 without breaking sweat. In fact, NVIDIA shared with us that the power savings with PureVideo HD (running on a VP2 engine) on a notebook is in the range of five to 10W as compared to solely utilizing the CPU. Depending on the notebook, this amount of power savings can equate to another 30 to 60 minutes worth of battery life.

Lastly, PowerMizer 7.0 has an improved PowerDimmer version 2.0. If you recall three years back, NVIDIA debuted the PowerDimmer function that automatically reduces brightness and contrast when no activity is present. The extent of how soon and to what level this feature kicks in was controlled via the power profiles. Version 2.0 builds upon its existing capability by gauging how much power is actually required to comfortably display the contents of the screen. As such PowerDimmer 2.0 dynamically (and constantly) modulates the LCD screen's backlight lamp power to achieve this high degree of power tuning and savings.

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