By default, the optimal configuration will be automatically selected in most cases. Manual configuration options should only be used as needed to support specific use cases, as instructed by Citrix Technical Support, or for troubleshooting and diagnostic purposes.
On VDAs version 7.16 and newer, administrators can pre-define how display adapters and monitors are configured for the user session using the following Windows Registry Key:
To select the preferred display adapter and assign usage priority (merits) for multiple display adapters
Value data [number]: Highest number gets the first preference
To restrict the number of monitors that can be created per display adapter
Value data [0-8]: depending on the number of monitors a GPU adapter can support
With the registry settings illustrated above, the administrator has configured the Citrix Indirect Display adapter with highest preference followed by the Nvidia adapter and maximum number of monitors allowed for both to 1. In this example, the session will use the Citrix IDD adapter for the primary monitor and the NVIDIA adapter for the secondary monitor, for a user connecting from an endpoint with two monitors.
There may be cases where using the Citrix IDD adapter (generic GPU support) is preferred or required, over the GPU vendor’s. Mainly as a troubleshooting step or a workaround to issues with GPU vendor adapters. For these cases the registry key may be configured with the single value as follows:
DWORD CitrixIDD = 3
Use Citrix IDD as a workaround to the following known issues:
Connecting to a VDA using Intel GPU from an endpoint with one or more monitors in portrait mode fails. This is a known issue with Intel drivers.
Connecting to a VDA with Nvidia GPU from an endpoint with 5 monitors results in the contents on the primary and 5th monitors being duplicated (mirrored).