Hi simonW I am not the original poster but I have downloaded windows 10 official build from the main site and would run into warnings on how my pytorch was not build from NCCL. I don’t have screen caps but I am positive I have ran into this problem. I haven’t touched pytorch in a while but I am fairly positive. Original version I had was from peterjc’s, once I saw official windows support I have since upgraded to 4.0.