Windows Server 2012 R2

Windows Server 2012 R2 is the server counterpart of Windows 8.1. It reached RTM on 27 August 2013 and was released on 18 October of that year. It replaces Windows Server 2012 and was replaced by Windows Server 2016.

This is the first version of Windows Server to drop support for processors without the CMPXCHG16b, PrefetchW and LAHF/SAHF instructions.

Editions
There are four editions of this operating system: Essentials, Foundation, Standard and Datacenter. As with Windows Server 2012, the Datacenter and Standard editions are feature identical, varying only based on licensing (particularly licensing of Hyper-V VMs). The Essentials edition has the same features as the Datacenter and Standard products, with some restrictions.

Changes

 * Automated Tiering: Storage Spaces stores most frequently accessed files on fastest physical media.
 * Deduplication for VHD: Reduces the storage space for VHD files with largely similar contents by storing the similar contents only once.
 * Windows PowerShell v4, which now includes a Desired State Configuration (DSC) feature.
 * Web Application Reverse Proxy.
 * Integrated Office 365 support.
 * The return of the Start button.

Hardware compatibility
Windows Server 2012 R2 is officially compatible with Intel processors up to Skylake (6th Generation). On Kaby Lake (7th Generation) up to Coffee Lake (8th/9th Generation), Server 2012 R2 is not supported due to a lack of Windows Update and Intel Graphics, however, hacks have been made to get both working. For Ice Lake (10th Generation) up to Alder Lake (12th Generation), no known hacks have appeared for Intel Graphics, but the chipset drivers for Ice Lake, Tiger Lake (11th Generation), and Alder Lake have been confirmed to install without any issues.