A computer enclosure includes a chassis having a rear wall, a transfer card, a mounting bracket, and a PCI card. An expansion slot is defined in the rear wall of the chassis. A detachable shielding cover is formed on the rear wall adjacent to the expansion slot. The transfer card is secured in the chassis. The transfer card has a circuit board perpendicular to the rear wall. The mounting bracket is secured to the rear wall of the chassis and has a width substantially equal to a length of the expansion slot. The PCI card is secured to the mounting bracket and perpendicularly attached to the transfer card. A receiving space corresponding to the shielding cover is defined shielding cover and the PCI card, for receiving a connector between the mounting bracket and the circuit board of the transfer card.