Hi there, My name is ***** ***** I am happy to assist!
The issue you are going to run into is that your desktop will need what is called a "low profile" video card. I would start your search there. However, low profile cards don't tend to be high end, as higher end cards, even low cost ones, tend to require a lot of cooling. So that is the trick you are in.
In general for towers, it should be fine. I would go with the beefiest Low Profile card you can find - although based on what I looked up on Newegg under low profile, there's nothing current there - there are some things though that will let you run Fallout though on medium settings and 60FPS.
Of course, happy to assist! There are some nice low profile cards that will do the job for sure. Also, if you could, please rate my customer service at the top from 1 star to 5 (5 being the best) as that feedback will help me with future tickets.