Unfortunately, there is a remarkable issue when it comes to Arabization in scientific/ technological terms.
In this case, the literal translation of Tower to Arabic is برج AKA Turret, which a false translation. Therefore, we must look for another definition to conserve and convey the right meaning of the source language.

And the closest translation will be :
English: Box / French: Boîtier / Arabic : صندوق الحاسوب
Definition (Wikipedia): "A computer case, also known as a computer chassis, tower, system unit, box, or cabinet, is the enclosure that contains most of the components of a personal computer."