How does one disable hardware acceleration in wpf?

You can disable it on a Window level starting from .Net 3.5 SP1.

public partial class MyWindow : Window
{
    public MyWindow()
        : base()
    {
        InitializeComponent();
    }

    protected override void OnSourceInitialized(EventArgs e)
    {
        var hwndSource = PresentationSource.FromVisual(this) as HwndSource;

        if (hwndSource != null)
            hwndSource.CompositionTarget.RenderMode = RenderMode.SoftwareOnly;

        base.OnSourceInitialized(e);
    }
}

or you can subscribe to SourceInitialized event of the window and do the same.

Alternatively you can set it on Process level:

RenderOptions.ProcessRenderMode = RenderMode.SoftwareOnly;

The precedence order for software rendering is:

1. DisableHWAcceleration registry key
2. ProcessRenderMode
3. RenderMode (per-target)

It is a machine-wide registry setting. See Graphics Rendering Registry Settings in the WPF docs for the registry key and other details relating to customizing WPF rendering.

The key listed is: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Avalon.Graphics\DisableHWAcceleration

The MSDN document is "not available" for .NET 4.5, so this may be a depricated option that only works in 4.0 or below.

In version 4.0, you can also use RenderOptions.ProcessRenderMode to set a process wide preference (http://msdn.microsoft.com/en-us/library/system.windows.media.renderoptions.processrendermode.aspx).

You can also disble hardware acceleration in WPF App by adding in MainWindow the following code.

protected override void OnSourceInitialized(EventArgs e)
{
    var hwndSource = PresentationSource.FromVisual(this) as HwndSource;

    if (hwndSource != null)
        hwndSource.CompositionTarget.RenderMode = RenderMode.SoftwareOnly;

    base.OnSourceInitialized(e);
}

This solved my issue with TeamViewer.

Source: How does one disable hardware acceleration in wpf?

That is a system wide setting, from the desktop, right click to bring up a popup menu, click on properties, and look around in there for the video settings to disable Hardware acceleration or that there may be a system tray icon for the graphics settings. This is system wide and not local.