When you deploy Windows Server 2012 R2 through Windows Deployment Services (WDS) Pre-Boot Execution Environment (PXE), the server CPU usage spikes to 100%. In this situation, client computers may freeze while waiting for a response from the PXE server. 


This issue occurs because of a race condition on the server that occurs in PXE operations that attempt multi-threaded network transfers. For example:

  • A high number of logical processors (32+ logical processors)

  • Multiple clients connect to a single PXE


To fix this issue, install the May 2016 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 (KB3156418).


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


Learn about the terminology that Microsoft uses to describe software updates.

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