On Windows: On Mac OS X:

NOTE: BOINC runs even if you don't use the screensaver.

When active, the screensaver does the following:

Normally, if you press a key or move the mouse while the screensaver is active, the screensaver will exit. Some BOINC applications handle keyboard/mouse input. If you hold down the control key, any additional input will be passed to the application, and your computer will remain in screensaver mode. "; page_tail(); ?>