Precision Mobile Workstations M4800/M6800 will not clone displays with Switchable Graphics enabled

Follow the guidelines below to resolve an issue with the Precision Mobile Workstations M4800/M6800 not cloning displays with Switchable Graphics enabled/ can't recognized graphics card after replace montherboard.

M4800/M6800 cannot clone displays

Precision Mobile Workstation M4800/M6800 system clone mode was not selectable for connected displays. User was able to extend graphics across all screens connected, but could not clone any displays.

NOTE: Systems with QHD or UHD displays will not have a Switchable Graphics Option See: Why the Precision Mobile Workstation M4800 systems may not have a Switchable Graphics BIOS option  for more details.

Disable switchable Graphics in BIOS

The system is working within the design specification.

These systems are equipped with Switchable graphics that allows the basic graphics adapter (Intel Integrated Graphics) to be the default graphics of the system. In this configuration, the high performance graphics card supported the external display.

To disable Switchable Graphics in the BIOS see Figure 1.

Figure 1. - Unchecking the Enable Switchable Graphics Option in the BIOS

The clone option is disabled when switchable graphics is enabled in the BIOS. If clone mode is required, then switchable graphics must be disabled.