A computer system is provided. The computer system includes a housing, a mainboard, a first heat source, a second heat source and a flow field modulator. An inlet and an outlet are formed on the housing. The mainboard is disposed in the housing. The first heat source is located on a first location of the mainboard. The second heat source is located on a second location of the mainboard. The flow field modulator is disposed on the mainboard including a control unit, a piezoelectric element and a guiding sheet. The control unit is electrically connected to the mainboard. The piezoelectric element is electrically connected to the control unit. The guiding sheet is connected to the piezoelectric element.