http://msdn.microsoft.com/en-us/library/ms797889.aspx
Windows Driver Kit: Display Devices
Display Hardware Acceleration Slider
The Display Properties dialog box has a hardware acceleration slider that can be helpful when you debug a display driver. By using the slider, you can set the display hardware acceleration support to one of six levels ranging from level 0 (full acceleration) to level 5 (no acceleration).
To find the hardware acceleration slider in Microsoft Windows XP, open the Display Properties dialog box and click the Settings tab. Click the Advanced button, and then click the Troubleshoot tab.
The following list describes the portion of hardware acceleration that is disabled at each level. Any feature that is disabled at a particular level is disabled in all subsequent levels.
- Level 0
- The slider is in the far right position. Hardware acceleration is fully enabled.
- Level 1
- Hardware cursor and device-bitmap support are disabled.
- Level 2
- The following display driver functions are not called. Instead, GDI performs the operations in software.
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- Level 3
- Microsoft DirectDraw and Direct3D support are disabled.
- Level 4
- Only the following graphics operations are accelerated.
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- Also, the following display driver functions are not called.
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- Level 5
- The slider is in the far left position. The panning driver (part of kernel-mode GDI) handles all rendering. GDI calls the display driver's DrvEnablePDEV and DrvEnableSurface functions to create a primary surface and also calls the display driver to set the display mode. The display driver is not called to do any rendering.
Another way to limit display hardware acceleration is to set flags in the CapabilityOverride registry entry. For example, setting the 0x2 flag in the CapabilityOverride entry is equivalent to placing the hardware acceleration slider at level 3. For a description of the CapabilityOverride registry entry, see Display INF File Sections.