mainboard atx schematic on
At best, the capacitance can be measured, if one of the two capacitors isn't shorted. You should be, aware, that more parts, e.g. the MOSFET switches can be damaged, too. The capacitor defect can be either a spontaneous event, at best with limited effect, or e.g. a result of an input overvoltage, most likely causing a far-reaching damage.
In either case, you should have an original schematic of the main board's power supply function, or a least sketch a partial schematic on your own.