title: CMD: powercfg -setacvalueindex with GUIDs does not work
body: <p>If I try to run this in CMD:</p>
  
  <pre><code>powercfg –setacvalueindex SCHEME_CURRENT SUB_VIDEO VIDEODIM 0
  </code></pre>
  
  <p>then nothing happens.
  If I try this:</p>
  
  <pre><code>powercfg -setacvalueindex SCHEME_CURRENT SUB_VIDEO VIDEOIDLE 300
  </code></pre>
  
  <p>then it works?</p>
  
  <p>What am I doing wrong?
  I can change those setting manually in Windows, so it should work automatically as well.
  Thanks in advance.</p>