Force IE8 to render in IE8 standard mode

Is there a way to force IE8 to always render a web site in IE8 standard mode?

I have tried to set the X-UA-Compatible to IE=8 but the local "Display intranet sites in Compability View" overrides it.

<customHeaders>
  <add name="X-UA-Compatible" value="IE=8" />
</customHeaders>