The answer to this question depends on the type of graphics card you have installed, and why it is causing your monitor to go to sleep.
It is possible that the graphics card is incompatible with your monitor and is not sending a signal through the video input port correctly. This can cause the monitor to go into a power-saving mode after a certain amount of time because it is not receiving the right kind of signal.
Another possibility is that the graphics card is generating too much heat, which can cause the monitor to shut off or go to sleep in order to protect itself. Too much heat can be caused by an insufficient cooling system, or simply an overly powerful graphics card being installed in a system that isn’t designed to handle it.
It is also possible that the graphics card has an incorrect driver installed, or an outdated version of the driver. This can cause the graphics card to perform poorly and generate too much heat, which can cause the monitor to shut off or go to sleep.
Finally, it is possible that the monitor’s power settings are set incorrectly. Monitors generally have several different power settings for varying amounts of usage. If the wrong settings are chosen, the monitor may shut off or go to sleep after a certain amount of time. It is recommended to adjust the power settings of your monitor according to the type of graphics card you have installed.
In summary, there are several reasons why a monitor might go to sleep after installing a new graphics card. These reasons range from compatibility issues to incorrect driver installations or power settings. It is important to make sure that the correct drivers are installed and that the power settings are set appropriately in order to prevent the monitor from going to sleep unexpectedly.