Since the announcement of Samsung’s Galaxy S4, there’s been much buzz about the Exynos 5 Octa chip that came with it. Folks tend to think of the Exynos 5 Octa having an octa-core CPU which, by number alone, will sound better than a quad-core counterpart. Truth is — the Exynos 5 Octa will only run at a maximum of 4 cores at a time, not 8.
We noticed that the misconception with a lot of consumers is that the Galaxy S4 (Exynos 5 Octa) can actually run all of the 8 CPU cores at one at maximum power.
In reality, only one of the 4-cores will run depending on the requirements. For most of the regular processes (SMS, calls, browsing, Twitter, FB, Instagram, Camera, etc), only the slower ARM Cortex A7 cores (200MHz to 1.2GHz per core). For more intensive number-crunching requirements, the faster ARM Cortex A15 cores will kick in (200MHz to 1.6GHz per core). This is what is referred to as the big.LITTLE architecture that we discussed here before.
The switching is done flawlessly on the hardware level so the OS or the system will never see this and will only recognize 4-cores at any time.
In hindsight, the Exynos 5 Octa is not really an octa-core chip but more of a 4+4 core chip in the same way that the Nvidia Tegra 3 is not a penta-core (5-core) chip but a 4+1 core chip.
So, the next important question now becomes — is the Exynos 5 Octa any better when it actually behaves like any other quad-core chip around, like the Snapdragon 600 which is also used in the Galaxy S4?
The answer — it depends. We know that the BIG core is powered by a 1.6GHz quad-core ARM Cortex-A15 so that will count for something. We have yet to see any benchmark results ourselves but we’re hoping it will perform better than the scores we got from the Galaxy S4 running a Snapdragon 600.