A new fan layout! We are fans.

Apple is changing things up quite a bit and has moved from multiple small fans to a single centralized fan.

"1" may be the loneliest number, but removing 2/3 of the fans goes a long way towards saving space.

Judging by the orientation of the squirrel cage fan, we gather that it draws cool air from the bottom vents, then blows hot air out of the grating in the back of the iMac.