Heat dissipation is the same as the S1 (ca. 360 W), so why not? Only with half the number of chips, heat production will be more concentrated, that's why there's a second heatsink on top of the chips. I assume the double fan configuration of the S3 is due to the closed box chassis, while the more open S1 is able to dissipate more heat to its local environment.

But assumptions ain't enough for me in this case.

EDIT: site BITMAIN is updated