Why is the power consumption of this etherent adapter so high?
How did you test that? Four Gigabit ports, this sounds standard for this kind of card.
I tested board without card and then with card, without connected ethernet cables.
http://en.wikipedia.org/wiki/Active_State_Power_Management
is ASPM supported by routerOS? Is it good idea to enable it on motherboard in bios?
4 NIC chips ( +/- 0.5 to 1 watt each) a bridge chip and supporting electronics.. 4-5 watt seems OK.
+1, yes, also my opinion. This will be similar to any such cards.
intel pro/1000gt consumes 0,5-1W
yes, because it has one port. x4 … 4
..you also need a bridge chip to connect 4 nics to 1 pci-e connector.