Take note that the screws are left-threaded. You shouldn’t exert yourself habitually trying to turn them to the right. The whole arrangement is fastened on the reverse side of the mainboard with nuts which are fastened with the help of a special gadget that you can turn with your screwdriver:

It is very convenient:

The nut doesn’t fall in and you can fasten it with any screwdriver, ordinary or cross-head. Unfortunately, Intel doesn’t seem to think that users may want to install a water-cooling kit, so their mainboard has some jutting elements on the reverse side of the PCB:

These elements don’t permit to put a back-plate on the reverse side of the mainboard, but it’s not a big problem. The pump/waterblock is not too heavy, so you can do without a back-plate:

The mainboard doesn’t bend much – no more than under an ordinary, box cooler. The pump is small and mounts easily on any mainboard: