MSI X99A XPOWER AC Guide Rapide page 45

SW-TACT1, SW-TACT2: Base Clock Control Buttons
These buttons are used to increase or decrease the base clock frequency. Pressing
the Plus/ Minus button once will increase/ decrease the base clock frequency
according to BCLK_STEP1 settings when the system is in regular operation state.
SW-TACT3, SW-TACT4: CPU Ratio Control Buttons
These buttons are used to increase or decrease the CPU ratio. Pressing the Plus/
Minus button once will increase/ decrease the CPU ratio when the system is in
regular operation state.
Plus button:
Increase base clock
Plus button:
CPU RATIO + 1
En-31
Minus button:
Decrease base clock
Minus button:
CPU RATIO - 1