One Small Step
While most articles surrounding the iPhone 6 and iPhone 6 Plus this far have focused around user experience and larger screen sizes, performance, and in particular the effect of Apple's transition to the 20nm process node for the A8 SoC have been our main questions regarding these new phones. Naturally, I decided to put my personal iPhone 6 though our usual round of benchmarks.
First, let's start with 3DMark.
Comparing the 3DMark scores of the new Apple A8 to even the last generation A7 provides a smaller improvement than we are used to seeing generation-to-generation with Apple's custom ARM implementations. When you compare the A8 to something like the NVIDIA Tegra K1, which utilizes desktop-class GPU cores, the overall score blows Apple out of the water. Even taking a look at the CPU-bound physics score, the K1 is still a winner.
A 78% performance advantage in overall score when compared the A8 shows just how much of a powerhouse NVIDIA has with the K1. (Though clearly power envelopes are another matter entirely.)
If we look at more CPU benchmarks, like the browser-based Google Octane and SunSpider tests, the A8 starts to shine more.
While the A8 edges out the A7 to be the best performing device and 54% faster than the K1 in SunSpider, the A8 and K1 are neck and neck in the Google Octane benchmark.
Moving back to a graphics heavy benchmark, GFXBench's Manhattan test, the Tegra K1 has a 75% percent performance advantage over the A8 though it is 36% faster than the previous A7 silicon.
These early results are certainly a disappointment compared to the usual generation-to-generation performance increase we see with Apple SoCs.
However, the other aspect to look at is power efficiency. With normal use I have noticed a substantial increase in battery life of my iPhone 6 over the last generation iPhone 5S. While this may be due to a small (about 1 wH) increase in battery capacity, I think more can be credited to this being an overall more efficient device. Certain choices like sticking to a highly optimized Dual Core CPU design and Quad Core GPU, as well as a reduction in process node to 20nm all contribute to increased battery life, while surpassing the performance of the last generation Apple A7.
In that way, the A8 moves the bar forward for Apple and is a solid first attempt at using the 20nm silicon technology at TSMC. There is a strong potential that further refined parts (like the expected A8x for the iPad revisions) Apple will be able to further surpass 28nm silicon in performance and efficiency.
Subject: Graphics Cards, Processors, Mobile | September 29, 2014 - 01:53 AM | Scott Michaud
Tagged: apple, a8, a7, Imagination Technologies, PowerVR
First, Chipworks released a dieshot of the new Apple A8 SoC (stored at archive.org). It is based on the 20nm fabrication process from TSMC, which they allegedly bought the entire capacity for. From there, a bit of a debate arose regarding what each group of transistors represented. All sources claim that it is based around a dual-core CPU, but the GPU is a bit polarizing.
Image Credit: Chipworks via Ars Technica
Most sources, including Chipworks, Ars Technica, Anandtech, and so forth believe that it is a quad-core graphics processor from Imagination Technologies. Specifically, they expect that it is the GX6450 from the PowerVR Series 6XT. This is a narrow upgrade over the G6430 found in the Apple A7 processor, which is in line with the initial benchmarks that we saw (and not in line with the 50% GPU performance increase that Apple claims). For programmability, the GX6450 is equivalent to a DirectX 10-level feature set, unless it was extended by Apple, which I doubt.
Image Source: DailyTech
DailyTech has their own theory, suggesting that it is a GX6650 that is horizontally-aligned. From my observation, their "Cluster 2" and "Cluster 5" do not look identical at all to the other four, so I doubt their claims. I expect that they heard Apple's 50% claims, expected six GPU cores as the rumors originally indicated, and saw cores that were not there.
Which brings us back to the question of, "So what is the 50% increase in performance that Apple claims?" Unless they had a significant increase in clock rate, I still wonder if Apple is claiming that their increase in graphics performance will come from the Metal API even though it is not exclusive to new hardware.
But from everything we saw so far, it is just a handful of percent better.