Key Differences Between Arm and x64
Arm and x64 CPUs have some fundamental differences in their design and intended use cases:
Arm is a RISC (reduced instruction set computing) architecture while x64 is a CISC (complex instruction set computing) architecture. RISC prioritizes simplicity and efficiency while CISC offers more complex instructions. Arm licenses its architecture to chipmakers while x64 is owned by Intel and AMD.
Arm focuses on power efficiency which makes it ideal for mobile devices. x64 focuses on maximum performance which is better suited for PCs and servers.
x64 has a longer 64-bit instruction set compared to 32-bit for Arm. This allows x64 to process more data per instruction.
x64 supports running both 32-bit and 64-bit software. The Arm 64-bit instruction set (A64) is not backwards compatible with 32-bit Arm.
Performance
When it comes to raw performance, x64 processors generally outpace Arm chips. There are a few key reasons for this:
x64’s CISC architecture can execute more complex instructions per clock cycle compared to RISC.
x64 CPUs have higher clock speeds, more cores, and larger caches than most Arm chips.
Intel and AMD have refined x64 for performance over decades while Arm is still maturing.
x64 benefits from advanced vector extensions like AVX that boost parallel computing.
However, Arm has been steadily reducing the performance gap with designs like Arm v8 and DynamIQ bringing multi-core and multi-threading advancements. Apple’s M1 Arm chips match or exceed Intel’s x64 processors in some benchmarks. But in most server and PC workloads, top-end x64 CPUs like AMD’s Epyc still outperform Arm.
Power Efficiency
This is where Arm shines. The inherent efficiency benefits of RISC architecture and Arm’s focus on mobile devices means Arm CPUs provide excellent performance per watt:
RISC’s simplified instructions require fewer transistors which reduces power draw.
No need to support legacy x86 instructions also saves power.
Arm SoCs integrate CPU, GPU, memory and more for efficiency.
Smaller manufacturing process nodes optimize Arm for low power.
x64 has made big improvements in power efficiency recently but still lags behind Arm. Even the top x64 chips like Intel Alder Lake use more power compared to Apple M1 to achieve the same workload. This efficiency gives Arm a significant advantage in mobile and embedded use cases.
Cost
Arm-based processors are generally cheaper than x64 CPUs due to a few reasons:
Arm licensing model spreads out design costs across licensees.
No backwards compatibility burden allows simpler and smaller Arm chips.
Manufacturing Arm requires fewer transistor layers, improving yields.
Prevalence in mobile gives Arm economies of scale advantages.
Intel and AMD have the cost advantage in the high performance space due to large existing x64 ecosystems. But Arm’s lower cost makes it very attractive for budget devices, allowing integration of advanced features at lower price points.
Software Support
Software compatibility is an area where x64 excels while Arm plays catch up:
Windows, macOS and Linux run primarily on x64, with limited Arm support.
Most existing applications are compiled for x64 only.
Arm Windows emulates x64 apps, hurting performance.
Open source Arm software is still maturing.
However, Arm software is improving quickly. ChromeOS runs well on Arm. Android has huge Arm app support. Apple’s investment in Arm Macs is encouraging more developers to build Arm-native apps. The future of software on Arm looks bright.
Market Share
x64 dominates the CPU market while Arm is still growing beyond mobile:
x64 owns 90%+ market share in servers and desktop PCs.
Arm has 95%+ share in smartphones and tablets.
Arm servers are still under 1% market penetration.
Apple’s transition to Apple Silicon is a big bet on Arm.
As more companies recognize the power efficiency benefits of Arm in data centers, enterprise adoption is expected to accelerate. The Arm server market is projected to reach 20% by 2025. Client devices like laptops will take longer to transition from x64.
Use Cases
Given the strengths and weaknesses outlined so far, here are the ideal use cases for each architecture:
Arm – Mobile devices, IoT/edge, energy efficient servers
x64 – Performance desktops, high-throughput servers, scientific computing
Of course, there is also overlap in applications where both can be deployed with some trade-offs. But generally, Arm suits low power and highly embedded uses while x64 is optimal for maximizing performance.
The Future
Rather than a winner-take-all outcome, Arm and x64 will likely continue evolving to own their distinct markets while competing at the edges. Some predictions for the future:
x64 retains edge in highest performance tiers.
Arm captures majority of mobile, edge and IoT.
Arm becomes a sizeable portion of data center servers.
More applications become cross-platform across both ISAs.
Specialized workloads may prefer one ISA over the other.
As software like Windows and applications become compatible across both Arm and x64, customers will enjoy more choice without compromise. The future is bright for innovative compute from both architectures.
Conclusion
Arm has key advantages in power efficiency and cost that lend well to mobility and connectivity. x64 is better suited for maximum computing performance and benefits from software maturity. While areas of overlap exist and the lines continue to blur, the specialized strengths of Arm and x64 will enable both instruction set architectures to thrive for the foreseeable future.