Microsoft Windows XP Professional x64 Edition released on April 25, 2005 is an edition of Windows XP for x86-64 personal computers. It is designed to use the expanded 64-bit memory address space provided by the x86-64 architecture.
The primary benefit of moving to 64-bit is the increase in the maximum allocatable random access memory (RAM). Windows XP 32-bit is limited to a total of 4 gigabytes. Although the theoretical memory limit of a 64-bit computer is about 18 exabytes (18 billion gigabytes), Windows XP x64 is limited to 128 GB of physical memory and 16 terabytes of virtual memory.
Windows XP Professional x64 Edition uses the same kernel and code tree as Windows Server 2003 and is serviced by the same service pack. However, it includes client features of Windows XP such as System Restore, Windows Messenger, Fast User Switching, Welcome Screen, Security Center and games, which Windows Server 2003 does not have.
Windows XP Professional x64 Edition is not to be confused with Windows XP 64-bit Edition, as the latter was designed for Itanium architecture. During the initial development phases, Windows XP Professional x64 Edition was named Windows XP 64-Bit Edition for 64-Bit Extended Systems.
- Supports up to 128 GB of RAM.
- Supports up to two physical CPUs (in separate physical sockets) and up to 64 logical processors (i.e. cores or threads on a single CPU). As such, As of 2014, the OS supports all commercially available multicore CPUs, including Intel Core series, or AMD FX series.
- Uses the Windows Server 2003 kernel which is newer than 32-bit Windows XP and has improvements to enhance scalability. Windows XP Professional x64 Edition also introduces Kernel Patch Protection (also known as PatchGuard) which can help improve security by helping to eliminate rootkits.
- Supports GPT-partitioned disks for data volumes (but not bootable volumes) after SP1, which allows using disks greater than 2 TB to be used as a single GPT partition for storing data.
- Allows faster encoding of audio or video, higher performance video gaming and faster 3D rendering in software optimized for 64-bit hardware.
- Ships with Internet Information Services (IIS) version 6.0. All other 32-bit editions of Windows XP have IIS v5.1.
- Ships with Windows Media Player (WMP) version 10. Windows XP Professional shipped with WMP 8, although WMP 11 is available for all editions of Windows XP.
- Benefits from IPsec features and improvements made in Windows Server 2003.
- Benefits from Shadow Copy features introduced in Windows Server 2003.
- Remote Desktop Services supports Unicode keyboard input, client-side time-zone redirection, GDI+ rendering primitives for improved performance, FIPS encryption, fallback printer driver, auto-reconnect and new Group Policy settings.
- Files and Settings Transfer Wizard supports migrating settings from both 32-bit and 64-bit Windows XP PCs
