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NVIDIA GeForce GTX 780 Review

Author: SKYMTL
Date: May 21, 2013
Product Name: GTX 780 3GB
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GPU Boost 2.0 Explained & Tested


When the GTX 680 was introduced, GPU Boost quickly became one of its most talked-about features. At its most basic, NVIDIAís GPU Boost monitored the power requirements of your graphics card and dynamically adjusted clock speeds in order to keep it at a certain power target. Since most games donít take full advantage of a GPUís resources, in many cases this meant Kepler-based cards were able to operate a higher than reference frequencies.

In order to better define this technology, NVIDIA created a somewhat new lexicon for enthusiasts which was loosely based upon Intelís current nomenclature. Base Clock is the minimum speed at which the GPU is guaranteed to operate at under strenuous gaming conditions, while Boost Clock refers to the average graphics clock rate when the system detects sufficient TDP overhead. As we saw in the GTX 680 review, the card was able to Boost above the stated levels in non-TDP limiting scenarios but the technology was somewhat limited in the way it monitored on-chip conditions. For example, even though the ASICís Power Limit could be modified to a certain extent, the monitoring solution took TDP as a relative term instead of factoring in additional (and essential) items like temperature.


In an effort to bypass GPU Boostís original limitations, the GPU Boost 2.0 available on TITAN and the GTX 780 will use the available temperature headroom when determining clock speeds. This should lead to a solution that takes into account critical metrics before making a decision about the best clocks for a given situation. The Power Target is also taken into account but you can now tell EVGA Precision or other manufacturersí software to prioritize either temperatures or power readings when determining Boost clocks.

While some other technologies described in this article will be eventually find their way into Kepler and even Fermi cards, GPU Boost 2.0 will remain a GK110 exclusive for the time being.


In order to better demonstrate this new Boost Clock calculation, we ran some simple tests on a GTX 780 using different temperature targets while running at a 106% Power Offset (the max available on this card). For this test we used EVGAís Precision utility with priority on the Temp Target.


The success of GPU Boost 2.0 is becomes readily apparent when different temperature targets and their resulting clock speeds are compared against one another. At default, the GTX 780 is set to run with a target of 80įC and a relatively pedestrian fan speed of between 30% and 50%, making it very quiet.

As we can see, voltage and clock speeds steadily decrease as the target is lowered. This is because the built-in monitoring algorithm is trying to strike a delicate balance between maximizing clock speeds and voltage, while also taming noise output and temperatures. With a TDP of some 250W, accomplishing such a feat isnít easy at lower temperatures so Boost clocks are cut off at the knees in some cases.

Increasing the Temperature Target to above 80įC has a positive impact, up to a certain extent. Since there are some limits imposed at GK110ís default Boost voltage (1.125V in this case), clock speeds tend to plateau around the 940MHz mark without modifying the GPU Clock Offset or core voltage.

This new GPU Boost algorithm rewards lower temperatures which will be a huge boon for people using water cooling or those willing to put up with slightly louder fan speeds. Simply keeping the Temp Target at its default 80įC setting and cooling the core to anything under that point will allow for moderately better clock speeds (up to 1GHz in our tests) with a minimum of effort. If youíre the enterprising type, a combination of voltage and a higher GPU Offset could allow a better cooling solution to start paying dividends in no time. Also remember that ambient in-case temperatures play a huge part in GPU Boostís calculation so ensuring a well ventilated case could lead to potential clock speed improvements.


As you can imagine, mucking around with the temperature offset could potentially have a dramatic effect upon fan speeds but NVIDIA has taken care of that concern. In the new GPU Boost, their fan speed curves dynamically adjust themselves to the new Temperature Target and will endeavor to remain at a constant frequency without any distracting rotational spikes.
 
 
 

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