Apple A7 vs Apple A8
Apple A7
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The Apple A7 is a high-end ARM SoC launched in September 2013 alongside the iPhone 5S. The chip can also be found in the iPad Air. It is one of the first ARM SoCs to implement the 64-bit ARMv8 ISA. The two CPU cores are clocked at 1.3 GHz (iPad Air: 1.4 GHz) and are based on Apple's Cyclone architecture. Furthermore, the chip also integrates a PowerVR Series 6 (Rogue) G6430 GPU and a 2x 32-bit LPDDR3 memory controller.
Architecture
Cyclone is the successor to the Swift architecture, which was used in the previous generation Apple A6/A6X SoCs (iPhone 5/iPad 4). The architecture is likely still a superscalar out-of-order design, but with significant revisions. Besides the new ARMv8 ISA, the chip offers various cryptography extensions (AES, SHA), extended registers and improved SIMD instructions. In combination with many other improvements like larger L1 caches and other optimizations, the performance per clock has been increased by about 50 percent. Even greater gains can be reported using 64-bit software.
Performance
Despite the low clock speed and only two CPU cores, the Apple A7 competes with other high-end ARM SoCs such as the Qualcomm Snapdragon 800. In software with poor parallelization like browser benchmarks, the A7 can outperform the entire ARM competition and be on par with the AMD A4-5000 or Intel Atom Z3770.
Graphics
The SoC integrates a PowerVR Series 6 (Rogue) G6430 GPU with 4 clusters. The G6430 offers more than twice the computing power of the SGX543MP3 in the Apple A6 and supports OpenGL ES 3.0 for the first time. The exact clock rate has not yet been confirmed, but it is probably in the 400 MHz range resulting in more than 100 GFLOPS. In the iPad Air, the GPU is clocked slightly higher at presumably about 450 MHz. Compared with other mobile graphics solutions, the G6430 performs similar to the tablet version of the Snapdragon 800 / Adreno 330 and is thus one of the fastest GPUs in its class. Therefore, even the most demanding iOS games of 2013 will run fluently.
Power Consumption
The A7 can be found in the Apple iPhone 5S, which offers a very long battery life despite its relatively low battery capacity. The chip is produced in a 28nm HKMG (High-K Metal Gate) process by Samsung and should have an estimated maximum power consumption of less than 2 - 3 W. In the iPad Air, the SoC should have a slightly higher TDP due to higher clock rates and less throttling.
Apple A8
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The Apple A8 is a high-end ARM SoC (System on a Chip) launched in September 2014 alongside the iPhone 6 and iPhone 6 Plus. The two CPU cores are clocked at 1.4 GHz (compared to the 1.3 GHz Apple A7) and are based on Apple's 2nd generation 64-bit architecture, called "Cyclone 2". Furthermore, the A8 integrates a PowerVR Series 6 (Rogue) GX6450 GPU and a 2x 32-bit LPDDR3-1333 memory controller.
Architecture
With Cyclone 2, Apple have managed to improve the already high performance per clock of the original Cyclone core (Apple A7) by another 10 to 15 percent. Neither Qualcomm's Krait nor ARM's Cortex-A57 can compete with the resulting IPC. The exact design changes have not been revealed, but we would expect enlarged caches and registers as well as an optimized branch prediction. As an ARMv8 architecture, Cyclone 2 is 64-bit capable.
Performance
Thanks to its impressive performance per clock, the Apple 1.4 GHz dual-core is a tough opponent for other high-end SoCs like the Nvidia Tegra K1 (4 cores @ 2.3 GHz) or Qualcomm Snapdragon 805 (4 cores @ 2.7 GHz). While the quad-core competitors win most multi-threaded benchmarks, the Apple A8 offers superior single-threaded performance, which is arguably more relevant for most everyday tasks like browsing. Overall, the A8 is one of the fastest smartphone SoCs as of late 2014.
Graphics
The SoC integrates a PowerVR Series 6 (Rogue) GX6450 GPU consisting of 4 clusters. Each cluster offers four FP16 and two FP32 ALUs, leading to a slightly higher shader performance than the former G6430. The core is predicted to be clocked relatively low at around 450 MHz (115 GFLOPS) to help reduce power consumption. According to our benchmarks, the GX6450 clearly outclasses the Adreno 330 in terms of 3D performance, but looses against Nvidia's more power hungry Tegra K1. Thus, the GX6450 is one of the fastest smartphone GPUs as of 2014 and can handle even the most demanding mobile games in high resolutions.
Power Consumption
In contrast to previous Apple SoCs, the A8 is manufactured by TSMC instead of Samsung. Using a brand-new 20 nm process, the SoC measures just 89 mm² and consists of about 2 billion transistors. Power consumption should be similar to or slightly below competing high-end SoCs by Qualcomm or Samsung.
| Model | Apple A7 | Apple A8 |
| Codename | Cyclone | Cyclone 2 |
| Clock | 1300 - 1400 MHz | 1400 MHz |
| L1 Cache | 256 KB | 256 KB |
| L2 Cache | 1 MB | 1 MB |
| L3 Cache | 4 MB | 4 MB |
| Cores / Threads | 2 / 2 | 2 / 2 |
| Transistors | > 1000 Million | 2000 Million |
| Technology | 28 nm | 20 nm |
| Die Size | 102 mm2 | 89 mm2 |
| Features | ARMv8 Instruction Set, PowerVR G6430 (4 Cluster Rogue), 2x 32 Bit LPDDR3-1333 Memory Controller | ARMv8 Instruction Set, PowerVR GX6450 (4 Cluster Rogue), 2x 32 Bit LPDDR3-1333 Memory Controller |
| Architecture | ARM | ARM |
| Announced | ||
| iGPU | PowerVR GX6450 |
Benchmarks
Average Benchmarks Apple A7 → 100% n=13
Average Benchmarks Apple A8 → 128% n=13
- Average benchmark values for this graphics card* Smaller numbers mean a higher performance
1 This benchmark is not used for the average calculation
