How to enable all 3 nvidia GPU running on the Zcash Minerv

So I just build a mining rig with 3 gtx1050ti 4GB card but the problem is when I turn on the miner, onky one of the graphics card works as the solver. How can I enable mining the other two graphics card? Please help!

Need more details.

What miner are you using? What OS? To start with…