weird error of Xeon Phi cards on running IMB

Hi,

I am using Intel MPI Benchmark to evaluate my Xeon Phi cards (5110p). Particularly, for the Pingpong test, all of my cards work well but one. This card will fail and automatically reboot when the message size of Pingpong test reaches 1G, which causes the benchmark to crash. Using micctrl -s to check the card, I observed that this card first became "lost", then "rebooting", and finally "online" again.

Any ideas?

Thanks!