A system for cooling a circuit component on an electronic device includes a closed-loop cooling circuit and a coolant filling device. The closed-loop cooling circuit includes a coolant block, a first pump and a radiator. The coolant filling device includes a container, a base and a second pump disposed inside the base. The coolant filling device is configured for attachment to the cooling circuit. In some embodiments, when the coolant filling device is attached to the cooling circuit, coolant may be circulated from the coolant filling device to the cooling circuit while the cooling circuit circulates coolant. In further embodiments, when the coolant filling device is attached to the cooling circuit, coolant may be circulated from the coolant filling device to the cooling circuit while the electronic device remains powered on.