Why ARM Is Overtaking X86: A Deep Dive into CPU Architecture Trends

Introduction

This article provides a comprehensive overview of the development, technical characteristics, and market dynamics of major CPU architectures, including x86, ARM, RISC‑V, and MIPS, and discusses how these trends affect servers, desktops, mobile devices, and emerging IoT applications.

Fundamentals of CPU Architecture

The central processing unit (CPU) is the core component of a computer, responsible for executing instructions and processing data. It works together with internal memory, input, and output devices, forming the three essential parts of an electronic computer.

Historical Milestones

In 1971 Intel released the first commercial microprocessor, the Intel 4004, a 4‑bit device fabricated with a 10 µm process, containing 2 300 transistors and running at 740 kHz. By 2020 the 11th‑generation Intel Core processors, built on a 10 nm process, integrated over a hundred billion transistors and reached a maximum frequency of 4.8 GHz.

Instruction‑Set Architectures: CISC vs. RISC

x86 (CISC) and ARM (RISC) represent the two dominant instruction‑set philosophies. CISC, originating in the 1960s, emphasizes complex instructions and strong single‑core performance, while RISC, formalized by Berkeley in the 1980s, focuses on a reduced instruction set, large register files, and streamlined pipelines, enabling higher instruction‑level parallelism.

Key Architecture Families

x86 (CISC) : Dominates servers, desktops, and many PCs. Intel’s early dominance created the “Wintel” ecosystem, which held a monopoly for over two decades. AMD’s recent EPYC processors have increased market share from 1 % to 8 % and aim for 15 %.

ARM (RISC) : Powers 90 % of smartphones and many embedded devices. Recent server‑grade ARM designs (e.g., Neoverse, Apple M1) achieve comparable single‑core performance to x86 while offering superior multi‑core efficiency.

RISC‑V (Open RISC) : An open ISA launched in 2010 by UC Berkeley. Its open‑source nature and low‑cost licensing have driven rapid ecosystem growth (133 % annual member increase in 2020) and positioned it as a third mainstream ISA after x86 and ARM, especially in IoT.

MIPS : Originally a Stanford project, still used in gateways, set‑top boxes, and some networking equipment, offering high performance per mm² and low power consumption.

Market Share and Trends

In non‑x86 segments, ARM holds the largest share (≈43 % of the overall CPU market), followed by RISC‑V and MIPS. ARM’s ecosystem benefits from low power, high integration, and extensive licensing models (PoP IP, IP Core, BoC, Architectural). RISC‑V’s open model lowers entry barriers, attracting a wide range of companies, including IBM, NXP, NVIDIA, Qualcomm, Samsung, Google, Huawei, and Alibaba.

Server‑side, non‑x86 shipments reached 8 060 units in 2019, a 60.2 % YoY increase, with revenue of $5.2 billion. By Q3 2020, non‑x86 server CPUs generated $16.4 billion (7.2 % of total server CPU revenue).

Domestic Chinese CPU Initiatives

China’s “Tai‑Shan” and “863” programs have fostered indigenous CPU projects such as Loongson (MIPS‑based), FeiTeng, Kunpeng (ARM‑based), and Sunway (Alpha‑based). These efforts aim to reduce reliance on foreign technology and build a sovereign computing stack.

Future Outlook

ARM is expanding beyond mobile into servers and desktops, driven by energy efficiency and heterogeneous computing advantages. RISC‑V’s open ecosystem is gaining traction in IoT and edge devices, with chip counts projected to reach 624 billion by 2025. Continued competition among x86, ARM, and RISC‑V will shape the next decade of semiconductor innovation.