Can a screensaver run on the Windows login screen?

A custom screensaver is a specially structured executable and has to support the expected command-line options and other Windows requirements. Even if it’s built correctly and installed for users, it still won’t run before anyone signs in because screensaver settings are tied to a user profile.

Third-party tools may be able to alter the sign-in screen, but that area is deliberately restricted for security and compatibility reasons. Those tools can be unreliable after Windows updates, so a lock-screen slideshow or managed background is generally safer than trying to run a full screensaver there.

For unattended school devices, configuring the display to turn off or putting the monitor to sleep through Group Policy or a device-management profile is usually the better approach. It saves power and avoids trying to modify the login process.

Traditional Windows screensavers only run inside an interactive user session, so they won’t start when the computer is sitting at the sign-in screen. The login screen can be customized to a limited extent, such as using a background image or rotating lock-screen images, but it doesn’t support normal screensaver programs.