The number of fans connected in series depends on the output of the motherboard. Motherboard fan connectors typically have an output of 1 to 2 amps. The current rating of our fans can be found on the back of the motor hub and under the technical details.
Example using the Liquid Freezer II 360: The water pump and the VRM fan together have 2.7 W/0.225 A and a P12 PWM fan has 0.96 W/0.08 A.
Water pump and VRM fans as well as 6 fans in push-pull configuration can easily be connected in series on a 1 amp motherboard connector.