Which slot are you using?  I have three 7070s with i350-T4 cards in the x4 slot and X540-T2 cards in the x16 slot.  To use the X540-T2 cards in the x16 slots I had to apply a fix that involves using tape to cover PCIe pins B5 and B6. Until I did the tape fix I would either get no boot or only show half of the RAM (64GB installed but only 32GB showing).
Hello everyone, I am a user in Taiwan I have an optiplex 5070 and use Dell i350 t4  when using 3 Slots memory is ok ,but use 4 the Computer won't turn on Have requested local technical support in Taiwan Taiwan Dell only replied that the optiplex 5070 is not compatible with Dell i350 nic 4 Even NOT collected HW error log .... Hope to get effective support here  
Dell optiplex 5070 is not compatible with Dell i350 t4 NIC