Fn+F7 is the screen streatching command - if you boot up and the display is smaller than the screen size, Fn+F7 will stretch it to the edges.  You are thinking of Fn+Z - that resets the BIOS routine that controls the fans.  If the temp is still high, the fans will come back on.  If you are experiencing the fans on alot or always, the 5100 is one notebook that needs the fan/heatsink assembly removed and the dust and lint cleaned all out for proper cooling.