I run multiple servers in my basement and the most important part of 'cooling' is extracting the waste heat and keeping good air flow. If new construction, are/can they place a vent or return in there?
I believe the simplest and cheapest solution (to be effective) is having a temperature controlled small inline vent fan above the computers / in ceiling that extracts the waste heat and moves the top layer of air in the room into the adjoining garage bay. If not temperature controlled, just run a small fan to move air into the garage 24/7. If the area is 'conditioned' to the rest of the house, place an insulated (keeps noise down) grate near the floor from the house into the storage room to pull in cool air, which should always be in the 60's (if this is your ground floor and no basement)) therefore you're not adding $30-100 a month in additional cooling for a tiny room if you had a dedicated cooling unit.
We had a mini-split built for my first business for a small server room and it was an icebox, which is a bit overkill.
You can use a furnace return grate in the ceiling of the room and a grate close to the floor to the house to move air from low to high and out. During the winter, I would just leave the room alone and the temp wouldn't get too bad. During the rest of the year, I just ran the furnace fan 24/7 to move air with a return above the servers and this was effective and cheaper than running a dedicated HVAC minisplit. It's possible that I may be reducing the lifespan of furnace fan by running it 24/7, but to me better that burning up a server.