I have a MSI Z170A mobo.

I have gotten 6 cards to be detected.  But 6th card does not behave properly.  Fans run at 100% and it mines very low hashrate.  Now 6th card is only detected if it is plugged into 16x PCI slot E_2 (silver colored) SLI slot.  If it is plugged into E_5 the other silver SLI x16 slot, it is not detected.  Even when I put 7th card, 7th card is not detected in E_5 and GPU in E_2 still runs fans at 100% and very low hash rate.

Anyone know what is going on and how to fix?