I don't know how to measure the direct power impact on a MacBook Pro (since it's got a battery), but the typical power consumption of these cards is 9 W, not much more than Aquantia 10 GBit cards.

Also, if you remember where you saw that logo, please let me know!

Plus 1-2.5w per active cable. You need the heatsinks as the cx4 cards expect active airflow, and active transceivers as well.

I have a 10gbit dual port card in a Lenovo mini pc. There is no normal way to get any heat out of there so I put a 12v small radial fan in there as support. It works great at 5v: silent and cool. It is a fan though so might not suit your purpose.