Try use -d option to specify only 1 GPU (GTX 970) to test and post result please.
it works fine with single gpu only
-d 0,2 -d 1,2 -d 0,1 don't work
Thanks for feedback. So Gpu0 is gtx970 and Gpu2 is gtx970 ? And 1 gtx 970 works fine (i.e. -d 0 works and -d 2 works). Okay, I have to investigate the problem.