A data processing system including a control chip, a central processing unit and a printed circuit board is disclosed. The control chip has a substrate stack that includes, from top to bottom, a first signal layer, a first reference layer at a first reference voltage, a second reference layer at a second reference voltage and a second signal layer. The central processing unit has a substrate stack that includes, from top to bottom, a third signal layer, a third reference layer at the first reference voltage, a fourth reference layer at the second reference voltage and a fourth signal layer. The printed circuit board has a stack structure that includes, from top to bottom, a fifth signal layer, a fifth reference layer at the first reference voltage, a sixth reference layer at the second reference voltage and a sixth signal layer. The second signal layer of the control chip and the fourth signal layer of the central processing unit are adjacent to the fifth signal layer. Critical signals may be transmitted from the central processing unit to the control chip via the third signal layer, the fifth signal layer and the first signal layer under a better return path.