2 networks 1 pc

I have a PC with database connected to 2 networks. NIC1 is configured for internet with IP address, subnet mask, gateway and DNS server, NIC2 is configured with IP address and subnet mask. In this configuration I cannot ping my NIC2 from outside. When I enter gateway for NIC2, I can ping both NICs, but it uses as default gateway NIC2, but I need it from NIC1. How to get this? How to make NIC1 to work for preffered card?