Anandtech, building on a post on a Beyond3D forum which claimed that the GPU in various models of the smartphone ran at higher clock speeds in certain benchmarks than in normal apps, said it found evidence that backed that assertion.
Not only that, the site said, it also discovered that the CPU was similarly affected in certain benchmarks.
The GPU behavior shown was a rise of 11 percent over what was otherwise the maximum speed at which the GPU would run -- 532Mhz vs. 480Mhz. Under no other circumstance than running one of the affected benchmarks could the GPU run at this speed.
The CPU, on the other hand, was set to its max speed when certain benchmarks were run. Notably, this differs from the GPU situation, in that the max speed is available to other apps, as well. It's just that when these benchmark tools are run the speed is pegged. The 532MHz max GPU frequency, however, is only available to specific benchmarks.
A search of code showed strings that implied specific benchmark apps were being targeted for higher clock speeds, but Anandtech did note that some affected benchmark did not have such "string evidence."
Samsung, in response, said:
Under ordinary conditions, the GALAXY S4 has been designed to allow a maximum GPU frequency of 533MHz. However, the maximum GPU frequency is lowered to 480MHz for certain gaming apps that may cause an overload, when they are used for a prolonged period of time in full-screen mode. Meanwhile, a maximum GPU frequency of 533MHz is applicable for running apps that are usually used in full-screen mode, such as the S Browser, Gallery, Camera, Video Player, and certain benchmarking apps, which also demand substantial performance.It's interesting that Samsung has the three words "certain benchmarking apps" in its response, although it continues on to say that the settings were not designed to improve benchmark results.
The maximum GPU frequencies for the GALAXY S4 have been varied to provide optimal user experience for our customers, and were not intended to improve certain benchmark results.
Samsung Electronics remains committed to providing our customers with the best possible user experience.
Ah, but they do. So why not set the frequency to 480Mhz for these benchmarks, if that is to be the typical frequency for a game that might "overload" the device.
Samsung's response does not give an explanation for the CPU speed difference, nor does it explain the "string evidence."