Direct3D 10 on Direct 3D 9 Video Card Resolution Limitation
Applies To: Windows 7
When using a Direct3D 9 video card with one or more monitors using a Single Large Surface resolution greater than 4096x4096 on Windows® 7, several of the new User Interface (UI) enhancements may not be available. Disabled UI enhancements include, but are not limited to:
Windows Aero – blurred and semi-transparent window borders
Windows Flip 3D
Windows 7 uses Direct3D 10 to render the UI. In order to maintain compatibility with older video cards, a translation layer, D3D10on9, is used. D3D10on9 has a 4096x4096 single monitor resolution limit. If a single monitor has a resolution larger than this limit the Desktop Window Manager (which handles many of the UI enhancements in Windows 7) will not run. You may also encounter this limitation if you use a video card that combines multiple monitors into one large display surface. This monitor configuration, known as a Single Large Surface, presents itself to Windows as one large high resolution single monitor. The desktop and taskbar spans multiple monitors. When you maximize a window, it will span all monitors.A Single Large Surface configuration is different from a Multi-Monitor configuration. With Multi-Monitor configurations, Windows is aware of multiple individual monitors. While the desktop still spans all the monitors, the taskbar and maximizing windows is limited to a single monitor. Multi-Monitor configurations are not affected by this limitation, unless one single monitor exceeds the 4096x4096 resolution limit while connected to a Direct3D 9 video card.You may also encounter limitations with other Direct3D 10 applications that use D3D10on9 under these conditions. In this case, the limitations encountered and resulting behavior will be application specific.
Windows 7 can still be used on Direct3D 9 video cards with a Single Large Surface greater than 4096x4096. The Desktop Window Manager; however, will not run and thus many of the new UI enhancements will not be available. You can work around this limitation by using a Multi-Monitor configuration or upgrading to a Direct3D 10 video card.
This limitation has been confirmed by Microsoft. It is an architectural limitation that only applies to the D3D10on9 translation layer.