Windows Server 2008 R2

Windows Server 2008 R2 is the server counterpart of Windows 7, which reached RTM on 22 July 2009 and was released on 22 October of that year, becoming the first server release to ship day-and-date with the client counterpart since Windows 2000 Server. This release drops support for the x86 architecture, a move which was followed by the consumer-oriented Windows 11 in 2021. It was also the last version of Windows Server to ship under the IA-64 architecture.

It is the last version of Windows Server to support processors without PAE, SSE2 and NX (update KB4088875 removes support for processors without SSE2), the last version of Windows Server to include the Enterprise and Web Server editions, and the last version of Windows Server that received a Service Pack from Microsoft. It is the last version to support upgrade paths from Windows Server 2003.

System requirements
Microsoft recommends Windows Server 2008 R2 to be installed on a system with a processor with a speed of at least 1,4 GHz, at least 1 GB of RAM, 32 GB of hard drive space, a DirectX 9-based WDDM display adapter or better display adapter, and a DVD-ROM drive.

Hardware compatibility
Windows Server 2008 R2 is fully compatible with Intel Skylake and earlier processor families. However, later processors are not officially supported as the Windows Update service is disabled and integrated graphics drivers do not properly function (although users have come up with workarounds to get both features working). In some cases, integrating USB 3.0 drivers into the installation media may be necessary in order to successfully install the operating system on modern machines due to the lack of USB 3.0 support, which was not introduced until Windows Server 2012. The P-cores and E-cores on Intel Alder Lake processors are incorrectly identified as being two separate processors in Windows Server 2008 R2.

Though no hacks currently exist to allow Intel Graphics to work on Ice Lake (10th Generation) and up, the latest chipset drivers still work on Windows Server 2008 R2.

Build 6801 introduced a feature internally known as "drift correction", which resolves issues related to CPU clock circuit timing that could potentially prevent either the operating system or services from starting up correctly. Clock drift/timing issues plague Windows Server 2008 on Intel Haswell processors and newer, as the OS will often fail to successfully boot to the desktop or cause many services to not function as a result of drift.