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. It was also the last version of Windows Server to ship with the IA-64 architecture and to receive a Service Pack from Microsoft.

This is the last version of Windows Server to support processors without PAE, SSE2 and NX (Update KB4088875 removes support for processors without SSE2) and include Enterprise Server and Web Server SKUs.

It replaces Windows Server 2008 and was replaced by Windows Server 2012.

Hardware compatibility
Windows Server 2008 R2 is fully compatible with Intel Skylake and earlier. Later processors aren’t officially supported as Windows Update is disabled and Intel Graphics do not work, though users have come up with hacks to get both working. In some cases, integrating USB 3.0 drivers into the installation media may be necessary in order to successfully install Windows Server 2008 R2 on modern machines due to lack of pre-integrated USB 3.0 support, which wasn’t introduced until Windows Server 2012. The P-cores and E-cores on Intel Alder Lake processor were incorrectly identified as dual processors in Windows Server 2008 R2.

Build 6801 introduced a feature internally known as “drift correction”, which resolves issues related to CPU clock circuit timing that can potentially prevent services from starting up correctly. Clock drift/timing issues plague Windows Server 2008 on Haswell and newer processors from Intel, where the OS will often not boot up successfully or boot up with many services having failed to start due to drift. Hobbyists are figuring out how to port this feature to Windows Server 2008 to resolve this problem.