Windows 8 is the first consumer version of Windows that not only runs on processors with the X86 architecture (from Intel and AMD), but also with processors with the ARM architecture. That makes it possible to compare the performance of these two architectures, which is exactly what we did. We used two ASUS tablets to find out what the difference is between the Intel Atom Z2760 and the Nvidia Tegra 3.
First a little background information, for those not as well-read about processor architectures. ARM is a different architecture than X86, which is the one traditionally used in PC processors from AMD and Intel. ARM processors speak a different language than X86 chips, which means that X86 software doesn't run on ARM processors and vice versa. However, more and more software is being developed to support multiple architectures. Linux, for example, has for many years now worked on various architectures, and last year saw the release of an ARM version of Windows 8 called Windows RT.
The two ASUS tablets used for this article, with on the left the VivoTab Smart (X86, Intel Atom Z2760) and on the right the VivoTab RT (ARM, Nvidia Tegra 3)
ARM: fundamentally different
ARM processors are fundamentally different than X86 CPUs. The ARM architecture is built around energy-efficiency, which is why it's so popular for use in smartphones and tablets. The energy-efficiency is due to the principle of the ARM, with the so-called RISC (Reduced Instruction Set Computer) chips. These processors can perform only a limited number of tasks, but can do those tasks very efficiently and fast.
Complex tasks have to be subdivided into a series of more basic instructions before the CPU can start to process them. X86 is different, it follows the CISC (Complex Instruction Set Computer) principle. The processors are able to execute a very large number of complex instructions, and need fewer steps for a certain task. This requires a large processor, which also increases the energy consumption.
Another important difference between X86 and ARM is the following. X86 chips are available only from three manufacturers: Intel, AMD and VIA, the last of which has a negligible market share. The owner of the X86 architecture, Intel, stopped selling licenses to other manufacturers years ago. Even if they had not, the huge investment it would take to develop a new X86 implementation would likely scare off any would-be manufacturers anyway. ARM is very open, on the other hand. Basically anybody is allowed to purchase an ARM license at a relatively affordable price, either for just the architecture or for the actual chip. It's no surprise then that there are a number of ARM chip manufacturers, including Qualcomm, Apple, Samsung, Nvidia and Texas Instruments.
Windows 8: market shift
Until recently the market was fairly clear-cut. X86 has had the monopoly among desktop PCs and laptops, and ARM owned the smartphone and tablet segment. The arrival of Windows 8 is causing a shift in the tablet market, however. Because Microsoft now has an OS that is designed with touch operation in mind, high-quality Intel-based tablets are starting to appear. At the same time the first Windows products with ARM chips are also seeing the light of day, with for example the Nvidia Tegra 3.
ARM chips are of course popular for mobile devices due to their efficiency. Intel's Atom processors are also aimed at the smartphone and tablet market, as the latest model is also a System-on-a-Chip (SoC) processor. Intel claims that the latest Atom is as efficient as ARM, while still offering high performance and compatibility with existing x86 software.
With the ASUS VivoTab RT (ARM, Windows RT, Nvidia Tegra 3) and the ASUS VivoTab Smart (X86, Windows 8, Intel Atom Z2760) we compared how the two architectures perform. This article will focus purely on the performance, we will publish a review of the ASUS tablets themselves in the near future.
The Nvidia Tegra 3 ARM chip as seen in Windows RT