title: SQL Server not using all CPU cores/threads on server hardware
body: <p>After upgrading our SQL Server's hardware, we noticed in the Windows Task Manager that the SQL instance is only using half of the "threads" available to it (see screenshot)<img src="https://i.stack.imgur.com/XWyHq.jpg" alt="Task Manager">. </p>
  
  <p>The server has the following hardware and software:</p>
  
  <ul>
  <li>Windows 2008 R2 Enterprise 64bit SP1</li>
  <li>Intel Xeon E7-4870 - 4 processors (40 cores, 80 threads)</li>
  <li>Microsoft SQL Server <strong>Standard Edition (64-bit) 10.0.4064</strong></li>
  </ul>
  
  <p>Running <code>select cpu_count from sys.dm_os_sys_info</code> returns 40.</p>
  
  <p>The OS sees all 80 threads. <a href="http://msdn.microsoft.com/en-us/library/ms143760.aspx" rel="nofollow noreferrer">SQL Server Standard Edition supports 4 Physical CPUs</a> which is what we have here. </p>
  
  <p>Why is only half the server's processing power being used?</p>
  
  <p>We have the same hardware and software on two servers and they both exhibit the same behavior.</p>