Can I set 2 times of batch size if I connect 2 TITAN RTX GPU cards by a NVLINK Bridge?

Hello everyone, I’m doing deep learning research, and I have already installed 2 titan rtx GPU cards and 1 nvlink bridge. I could set batch size as 8 before I installed nvlink and I expected that I could set batch size as 16 after I install nvlink bridge, but it turns out that it doesn’t work…Please help me solve this issue, thank you in advance!

here is the information of my machine:
OS: ubuntu16.04
Driver: 410.79
GPU card: titan rtx x 2