More Exynos 5420 Octa details revealed by Samsung

Following the official release of the Exynos 5420 Octa two weeks ago, Samsung has released more details and features of the new chipset.

The new Exynos 5420 packs four Cortex A15 and four Cortex A7 CPUs utilizing the same big.LITTLE architecture as the current Exynos 5410 found in some variant of the Galaxy S4. By optimizing the power-savings design, Samsung is able to clock the Exynos 5420 higher at 1.8 GHz for the Cortex A15 CPU and 1.3 GHz for the Cortex A7 CPU. In comparison, the clock frequency for the Exynos 5410 is 1.6 GHz for the Cortex A15 CPU and 1.2 GHz for the Cortex A7 CPU. With the increased clock speed, Samsung promises to deliver about 20 percent more CPU performance. The new Exynos 5420 also features a larger memory bandwidth (14.9 GB/s versus 12.8 GB/s) due to its LPDDR3 unit running at 1866 MHz as oppose to Exynos 5410′s 1600 MHz.

As previously mentioned, Samsung has switched from a PowerVR SGX544MP3, to a Mali-T628 MP6 (six-core) GPU, which offers two times more graphical performance over the former. With the support for GPU computing on Mali-T628 MP6, Samsung indicates that the Exynos 5420 will accelerate certain applications such as image stabilization and editing, facial detection and open-eye detection. Another advantage of GPU computing is the ability to offload certain tasks from the main application processor. According to Samsung, GPU computing significantly increases the power-efficiency and provide longer battery life for mobile devices powered by the Exynos 5420.

The Exynos 5420 also support Mobile Image Compression (MIC). This feature compresses image in the buffer such that it is more power-efficient to transfer images from the memory to the display panel. It is particularly useful in minimizing power consumption of a constantly-refreshing high-resolution display during media playback.

With the Exynos 5420, Samsung reportedly also fixed the CCI-400 coherent bus interface bug that is troubling the current Exynos 5410. The CCI-400 coherent bus interface is the communication interface between the Cortex A15, the Cortex A7 and the rest of Exynos 5410 SoC. In the Exynos 5410 implementation, the CCI-400 coherent bus interface is broken such that every time when a application switches between the Cortex A15 and the Cortex A7, the information in the cache is flushed to the memory. The wasted cycles to transfer data between memory and cache every time during a switch represent a huge power overhead.

Although no official words from Samsung, the new Exynos 5420 is expected to be featured in some variant of the Samsung Galaxy Note III and the successor of the current Galaxy S4.