Home : Hardware Terms : x86-64 Definition


x86-64 is a 64-bit version of the x86 processor architecture, which Windows PCs have used for several decades. It is similar to x64, but refers specifically to processors that use the x86 instruction set.

CPUs with the x86-64 architecture run in 64-bit mode by default, but are also backward-compatible with 32-bit and 16-bit applications. In other words, any program that runs on a 32-bit x86 CPU should run on an x86-64 CPU with no emulation required.

The main benefit of an x86-64 processor versus a standard 32-bit x86 CPU is significantly more addressable memory. A 32-bit processor can only reference 232 (4,294,967,296) addressable values in memory — roughly 4 gigabytes. A 64-bit processor supports 264 (18,446,744,073,709,551,616) addressable values. Therefore, an x86-64 CPU does not support double the memory of an x86 CPU, but 4,294,967,296 times more.

Read more about the difference between 32-bit and 64-bit systems in the TechTerms Help Center.

Intel and AMD are the two primary manufacturers of X86-64 processors. The two technologies are labeled Intel 64 and AMD64, respectively. AMD released its first 64-bit CPU (Operteron) in 2003, followed shortly by Intel, which released its first 64-bit CPU (Nocona) in 2004. Today, nearly all processors are 64-bit.

Updated: March 6, 2021

Cite this definition:


TechTerms - The Tech Terms Computer Dictionary

This page contains a technical definition of x86-64. It explains in computing terminology what x86-64 means and is one of many hardware terms in the TechTerms dictionary.

All definitions on the TechTerms website are written to be technically accurate but also easy to understand. If you find this x86-64 definition to be helpful, you can reference it using the citation links above. If you think a term should be updated or added to the TechTerms dictionary, please email TechTerms!

Subscribe to the TechTerms Newsletter to get featured terms and quizzes right in your inbox. You can choose to receive either a daily or weekly email.

Sign up for the free TechTerms Newsletter

How often would you like to receive an email?

You can unsubscribe at any time.
Questions? Please contact us.