yeah a lot of store bought pc's (dell, hp etc..) will use a tower style heatsink and a duct to help the rear case fan pull hot air from the heatsink. You can also liquid cool or even phase change. but somewhere along the line there is likely going to be a heatsink and a fan.
When I first recieved my last PC the heat sink had come off in transit (shoddy stock intel cooler with those annoying push-twist pins thingies). The computer wouldnt load windows, after POST the screen would read "processor temperature error" and then the computer would switch itself off.