... have discrete graphics subsystems and 13.3-inch displays. P/N: 599518-001 Laptop motherboard for HP ProBook 4321s Series Motherboard 599518-001 ... of fittings, rust, rot, heat elimination chassis.4. check internal and external connector of LCD display , Two memory, DVD driver, ... SD connector, PC, 3.3V COMS battery, Battery whether charge and discharge,Full running 3D, Restart system at least two times ...