Comment on Autopsy of a Freshly Cooked 10Gbit SFP+ Network Adapter by Allan-H

The early ones (~ a decade ago) used Aquantia PHYs and the reach was limited to 30m (down from the usual 100m cable length specification) just to limit the power dissipation in the PHY in the SFP module. The PHYs adjust the transmit power to achieve a certain SNR at the receiver. Shorter, lower loss cables actually cause the PHYs to use less power, run at lower temperatures and last longer.

Aquantia was later bought by Marvell.