i am planning a custom loop and i already checked out all the parts i want to use, i am going to use an ek x-res 140 reservoir with a d5 pump combo and according to a couple of build logs i have seen i may have to drill a hole into the top of the hard drive cage in order to fit it where i want to use it, or i can velcro it to the top of the cage but i won't be able to use the speed dial, will drilling two holes into the hdd cage void the warranty of the fractal design define r4
Drilled holes, void warranty on case = yes.
Just set the speed to 1 or 2 on the D5. Both of which move plenty of water for 99% of wc loops.
Very high quality adhesive velcro strips or double sided automotive tape can work well. Be sure to test it though to make certain it can hold the weight.