Hi.
How about some third word solution? It is eco-AC, without electricity only works thanks to power of physics. (and yes, it works)
Wont reduce the temperatures to subzero but at least its basically free.
I think its like with RAM, never to much of it so if you can reduce the temp. even about 1 degree, it's worth to try. Additionally its fun to make and gives cool contrast with high-tech bitcoin miners Just saying...