I'm not familiar with Dell product names specifically but 'tower' sounds like it'll sit there burning 200W idle. Old laptops (sliding out the battery) is what I've been opting for, which use barely anything more than the router it sits next to. Especially if you just want to serve static files as GP seems to be looking for, an old smartphone will be enough but there you can't remove the battery (since it won't run off of just the charger)