Samsung had quite a rough time with its Exynos 5 Octa version of the Galaxy S4 and mainly due to some delays and the fact that it lacked LTE support in the initial batch were just a couple of reasons for Samsung to switch to Qualcomm's Snapdragon 600 in its I9505 model while Samsung I9500 was only available in a couple of regions. To make matters worse, it now appears that Samsung was caught cheating in benchmarks with its Exynos 5 Octa chip.
It is known for quite some time that Exynos 5 Octa version of the Galaxy S4, or simply the Samsung Galaxy S4 I9500 was slightly faster in benchmarks but also had a slightly weaker battery life. According to Anandtech.com, it appears that this boost in performance comes from a rather simple but quite effective trick as the GPU part of the Exynos 5 Octa, the PowerVR SGX 544MP3 gets overclocked when you run a benchmark.
Although Samsung never officialy revealed the precise GPU clock of the Exynos 5 Octa in Galaxy S4, Anandtech discovered that GPU works at 480MHz in most scenarios, or to be precise, it works on 480MHz unless you are running benchmarks, when it clocks up to 532MHz. This means that those benchmarks do not represent the actual performance and is simply considered as cheating. It does a pretty same thing with the CPU part as well, which behaves suspiciously but can't be considered cheating as it is also available whenever needed and in other apps as well.
Good side of the story is that the Exynos 5 Octa Galaxy S4 does not cheat in all benchmarks but most important ones like Antutu, Quadrant, GL Benchmark 2.5, BenchmarkPi and Linpack are all affected.
It looks like Samsung was caught with its pants down when it comes to Exynos 5 Octa in the Galaxy S4 and apparently tried to make it look faster than it actually is and we are quite sure that Qualcomm is quite happy right now.
Source:
Anandtech.com.