RISC-V vs ARM vs x86: The Honest Comparison

RISC-V, ARM, and x86 are instruction set architectures, or ISAs. An ISA is the contract between software and hardware: the set of instructions a processor understands and the rules for how they behave. It is not a chip and not a company. It is a specification that chips implement and that compilers target.

Most comparisons of these three get lost in old debates about RISC versus CISC. That framing is mostly outdated. The differences that actually shape the industry are licensing, ecosystem, and momentum, and all three moved in the last two years: Intel and AMD formed an x86 Ecosystem Advisory Group in October 2024, Ubuntu 26.04 LTS made the RVA23 profile the minimum for RISC-V, and on 13 October 2026 a Delaware jury found that Arm breached its architecture license agreement with Qualcomm. The full timeline is in the section on what has changed since October 2024, below.

What x86, ARM and RISC-V are#

x86 is the instruction set of Intel's and AMD's processors and the one the Windows PC was built on. It is a CISC design with a long history, and crucially it is closed. In practice it is controlled by two companies, Intel and AMD, who settled their patent disputes in 2009 with a cross-license agreement; a third x86 line survives in China through Zhaoxin, whose KX-7000 is an eight-core x86 chip, but there is no open door to walk through. You cannot simply license x86 and build your own compliant chip. In October 2024 the two formed the x86 Ecosystem Advisory Group with Broadcom, Dell, Google, HPE, HP, Lenovo, Meta, Microsoft, Oracle and Red Hat to keep x86 features consistent across their products, but that is a forum, not a license. Its great strength is an enormous base of existing software, much of it commercial and much of it decades old, compiled for x86. That inertia shows even on Apple silicon Macs, where Apple's developer documentation says an app built only for x86_64 must run under Rosetta translation.

ARM is a RISC design owned by Arm Holdings, which SoftBank Group bought in 2016 and which listed on Nasdaq in September 2023; SoftBank reported owning 89.8 percent of Arm's shares after the listing. Arm says more than 99 percent of the world's smartphones are based on its technology. Arm sells access two ways: you can license a ready-made core design, such as the Cortex line, and drop it into your chip, or you can take an architecture license and design your own compliant core from scratch. Qualcomm's custom Oryon CPU cores are architecture-licensed designs, and Apple designs the chips in its Macs, which run the 64-bit ARM instruction set (arm64 in Apple's developer documentation). Either way you pay, and you operate within Arm's rules. Its strength is a mature, power-efficient design with an ecosystem that now reaches from the smartphone into the data center: AWS's Graviton5 has 192 Arm Neoverse V3 cores, and NVIDIA's Grace CPU Superchip packs 144 Arm Neoverse V2 cores.

RISC-V (pronounced risk five) is the newcomer and the structural outlier. It is an open, royalty-free standard ISA, governed by the non-profit RISC-V International, which is incorporated in Switzerland. Anyone can implement it, in open or proprietary designs, without paying a license fee for the instruction set itself. That openness is the whole point and the whole story. Today it is mostly where you do not look: microcontrollers such as Espressif's ESP32-C3, and the small control cores inside larger chips; NVIDIA says it passed one billion RISC-V cores shipped in 2024, with typically 10 to 40 in each chip. It also sits in custom AI accelerators: Meta's first-generation MTIA inference chip uses RISC-V processor cores. SiFive and Tenstorrent design high-performance RISC-V cores for other chipmakers, and Alibaba's XuanTie line includes a server-grade RISC-V chip. What it does not yet have is a mainstream application processor in the phones and laptops most people use. The first Framework-compatible laptop board with an RVA23-class chip went on sale in May 2026, and its maker says the bundled Ubuntu build is for developers and not production-ready.

RISC-V vs ARM vs x86 side by side#

Read down the licensing row and the real divide appears. x86 is a club you mostly cannot join. ARM is a club you pay to join and must follow the rules of. RISC-V is open to everyone. That single difference, more than any technical detail, is what pulls companies that want to control their own silicon toward RISC-V.

Does RISC vs CISC still matter?#

The textbook story is that RISC uses simple, uniform instructions while CISC uses complex, varied ones, and that this difference drives performance and efficiency. In practice, modern high-performance chips of all three kinds do something similar under the hood: they break incoming instructions into smaller internal micro-operations and execute those out of order, with elaborate machinery for parallelism and branch prediction. The ISA visible to software is, by the execution stage, an abstraction the chip has already translated away.

There is one place the ISA genuinely leaks into the hardware: the front end, where instructions are fetched and decoded. x86's variable-length encoding means a chip does not know where the next instruction begins until it has worked out the length of the current one, which makes decoding many instructions per cycle harder and pushes x86 designs to lean on micro-op caches to hide the cost. ARM's 64-bit instructions are fixed-length, and RISC-V's are fixed-length or cleanly compressed, which makes them simpler to decode several-wide in parallel, though high-performance ARM cores use micro-op caches too. This is a real engineering difference, but it is a second-order one, and it is swamped by everything else.

Because of that, you cannot predict whether a chip is fast or efficient just from knowing its ISA. Implementation quality dominates: the specific design of the cores, the manufacturing node, the cache hierarchy and memory system. Chips and Cheese, comparing ARM and x86 cores, put it plainly: the instruction set is not what matters, the design of the CPU implementing it is. A great core and a mediocre one on the same ISA are worlds apart. The ISA sets some constraints; it does not determine the outcome.

The three differences that decide it#

Three differences are genuinely decisive, and none of them is about instruction decoding.

Licensing and control. This is the headline. RISC-V lets a company build a processor without paying for the ISA and without asking permission, which matters to anyone who wants full control of their silicon or wants to avoid dependence on a single licensor. That dependence is not hypothetical. Arm sued Qualcomm over the cores Qualcomm acquired with the Nuvia startup. A jury found in December 2024 that Qualcomm did not breach Nuvia's license, and on 30 September 2025 the court entered final judgment for Qualcomm and Nuvia and rejected Arm's request for a new trial; Arm filed a notice of appeal the next day. Qualcomm's own suit against Arm then went to trial, and on 13 October 2026 a Delaware jury found that Arm had breached its architecture license agreement with Qualcomm, while awarding only one dollar on each claim it upheld. However the remaining rounds go, years in court over one licensor's terms is exactly the strategic risk RISC-V removes by removing the licensor.

Software ecosystem. x86 has decades of Windows and server software behind it. ARM leads mobile and has moved into the Mac and the cloud, with Apple silicon, AWS Graviton and NVIDIA Grace. RISC-V's software stack is real and growing but younger, which means more gaps to fill depending on what you are building. Filling those gaps is exactly why the RVA23 profile, ratified by RISC-V International in October 2024, matters: it makes vector and hypervisor support mandatory, so operating-system and application vendors can target RVA23-class chips instead of a fragmented field of incompatible variants. It has become the common line: Google made RVA23 the baseline of the Android RISC-V ABI, Ubuntu 26.04 LTS runs only on RVA23S64 hardware, and Tenstorrent says its TT-Ascalon CPU is fully compatible with the profile.

Customization. Because RISC-V is open and designed to be extended, teams can add custom instructions tuned to their workload, which is powerful for AI accelerators and specialized embedded silicon. On x86, only Intel and AMD decide what gets added; on ARM, what you may change is set by your license. Meta's first-generation MTIA inference chip, built for its ranking and recommendation models, shows the RISC-V approach: a grid of 64 processing elements, each with two RISC-V cores, one of them equipped with the vector extension. The catch is the flip side of that freedom: the same extensibility invites fragmentation, because a binary compiled for one vendor's custom extensions may not run on another's. Openness cuts both ways, and profiles like RVA23 exist precisely to hold a common, portable core together underneath all the customization.

What changed since October 2024#

Which ISA should you choose?#

The honest summary: these three differ far more in business model and ecosystem than in raw architectural merit. The RISC-versus-CISC debate is a distraction. Licensing, software support, and design quality are where the real decisions get made.