Not to get too far off the subject here, just responding to the post with the videos about liquid cooler mounting:
GNSteve and JayZ have both been wrong about plenty, and that's coming directly from someone with 40+ years of experience in computerized systems maintenance, formal training at the best US Navy school in Avionics (AVI-C7) and for actual Navy flight simulator maintenance (specifically, this includes liquid dynamics/hydraulics).
Neither the lines going to the radiator nor the pump head assembly should be the highest point in the system.
Not sure why the bottom picture would say "this is fine", because it's not. The hoses should never be at the top of the radiator.
Arguably, there **might* be enough liquid at the top to submerge both lines inside and thus avoid air void binding...but I'd doubt it, and I wouldn't suggest it's worth taking the chance.
Edit: The stupid thing is that, often, the actual instructions for mounting these things are all kinds of wrong. In most cases, they say to mount the unit so that outside air can be blown directly over the radiator. This will (almost invariably) lead to air - heated by whatever the liquid system is cooling - being forced *in* to the chassis. Last I checked, we want to remove heated air from the system, not introduce more. While there's little doubt that, it's better to use cooler air to blow at a radiator, this ceases to be a good idea the moment it results in dumping hot air into the box we're trying to cool.