I think you will find that from a hardware point of view the IO Board is fine, the problem is that the version of firmware you are running does not support them.
Rich
Really? S7 Batch 1 firmware, haven't upgraded?
Read this
https://bitcointalk.org/index.php?topic=1173573.015 september 2015 software support 6 blades
I have today 5x S7 with 6 blades.
All with File System Version Tue Sep 15 16:50:19 CST 2015