With your windows machine whilst you may have configured the dual nic, in reality it can only use ONE route, this is from MS Support
For your SM board to use both nic's is to configure two different subnets then you would route the subnets to communicate, none of this is necessary within a simple network at home.
If you could do the same as your windows machine it would make no difference as a network packet will only use one route.
The best option for that SM board is to use the IPMI nic for that purpose and configure the other LAN and WAN (WAN for updates). Another alternative is to perhaps configure the IPMI nic for internal networking, so all yours machine point to that IP for shares etc, but that may create additional work.
Raid is not a backup! Would you go skydiving without a parachute?