Asus Rampage IV Formula - Manual (Page 40)

2-16 Chapter 2: Hardware information
Chapter 2
5. PCIe x16 Lane switch
These slide switches allows you to enable and disable the corresponding PCIe x16
slots. When one of the installed PCIe x16 cards is out of order, you can use the slide
switch to find out the faulty one without removing the cards.
6. Q reset button
If the LN2_Mode jumper does not work and your CPU cannot resume function, press
the Q reset button to temporarily stop the power supply to the CPU and help the CPU
recover from a frozen condition.