A printed circuit board (PCB) includes a signal layer and a power layer. The signal layer includes a crystal oscillator pad, a clock generator pad, and two capacitor pads. The crystal oscillator pad is connected to the clock generator pad and the capacitor pads via two signal lines. The power layer is divided into two areas by a cut-off line, the two areas respectively having different voltages. The cut-off line is located at one side of the crystal oscillator pad and the clock generator pad.