What does CTRL+WIN+SHIFT+B do in Windows?

This key sequence actually restarts you graphics driver.

Official from Microsoft: "Windows logo key + Ctrl + Shift + B = Wake PC from blank or black screen"

From a discussion with an AMD Radeon driver engineer, it does NOT restart the graphics driver. It does appear to discard the desktop surface buffer and re-create the allocation from DWM (on a healthy system the desktop goes black for a second).