Cooling a few GPUs

As summer is already here and plans are in motion to add more computing power to the small mining farm, i’m working on a better cooling solution for my mining computers.
The images show the work in progress of my cooling closet.

The idea was to take an ikea PAX cabinet, cut a few holes in it, and use outside ambient temperature air to do the cooling of the GPUs. The hole on the bottom draws outside air into the closet, and the inline exhaust fan at the top blows the hot air outside, creating a sort of wind tunnel inside the cabinet.
The fan up top is an inline exhaust fan that can do about 1000CFM, and I picked it up kn kijiji a while ago for a bargn. It should provide enough cfm to move quite a bit of air through the closet. I will have to seal the doors , and since there will be a bit of a vacuum inside closet, this will only serve to keep the doors closed and sealed.
The inside consists of aluminum rails which hold wooden frames. Currently working on the ideal wooden frame for this setup, and will publish the design once I’m happy.
A lot of mining equipment photos show shelves of computers and GPUs working away, but the air that the GPUs use to cool down is essentially the came air that they heat up, leading to ever increasing temperatures. The idea of what I’m doing is that the GPUs are always exchanging their heat to outside air, rather then the same air that they heat up. Maintaining the air that is used to to cool at a constant temp (outside ambient air temp) will make the GPU’s fans work less hard to maintain cool temperatures of the GPU.
One advantage of this type of cooling is that is scales very easily. Need to cool more GPUs? No problem. Repeat the process and add more cooling closets. The outside air temp will not be influenced by whatever hot air you’re dumping out.