I'm an older man; and here is my thought based on 31 years in electronics: 1- It does matter vertical or horizontal; But: 2- to know exactly which way: you have to open one drive of they type you want to use for long term and study all the ElectroMECHANICAL components and effects. Just to give u a simple confusing; if horizontal is better for gravity point of view; then you should know that many pallaters have arms under the plate also; so good for one side, bad for the other, ... and so on.
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