I needed to know because I bought an old blue-and-white G3 (used) at a college PC sale, and I've been trying to kit it out as much as possible and wanted to determine whether I could get away with buying sleeve bearing fans to save a bit of money, but didn't want to do so if the brackets were in the...

The articles say to only use them if you're mounting them vertically. I ask: What is meant by "vertical"? Do you mean that the axis around which the fan rotates is vertical? Or do you mean that the fan rotates within a vertical plane? The wording leaves me guessing. I don't want to be left guessing ...