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IT Support & Hardware · Foundational

x86-64 Architecture (x64)

The 64-bit extension of the x86 instruction set used by most Intel and AMD PC processors.

Definition

x86-64 (also called AMD64 or Intel 64) extends 32-bit x86 to 64-bit registers and a vastly larger address space while still running 32-bit code. A 32-bit OS can address only about 4 GB of RAM, while a 64-bit OS can use far more. Windows 11 is 64-bit only.

Example

Windows shows 'System type: 64-bit operating system, x64-based processor' in Settings > System > About.

Exam tip

A 32-bit OS limits usable RAM to roughly 4 GB regardless of how much is installed.

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