16633, J1A4 connector on the LSI 3ware 9750 should not be used for I2C.
This is the Install guide for the 9750: http://www.lsi.com/downloads/Public/RAID%20Controllers/RAID%20Controllers%20Common%20Files/45412-01C_9750_install_Guide_final_050610.pdf
The install guide references J1A4:
Here
It is defined in Table 8 as 'IPMI-style' I2C.
Do no use this connector. For I2C support, see these KB articles:
9750 with ‘TQ’ style backplane: http://kb.lsi.com/KnowledgebaseArticle15858.aspx
9750 with ‘A’ style backplane: http://kb.lsi.com/KnowledgebaseArticle16146.aspx