I recently removed my 25Gbps PCIe dual port cards from my 2 servers because they were using 20W more. My entire rack including 2 UniFi PoE connections uses 90 W now (so 110 W just for having 25 Gpbs).
There is some heat from such cards, but usually it gets transported outside fine. The ones I bought did not come with a fan. I think you cannot operate them without one. The heat sinks get very hot.