X99-E WS More than 5 graphic cards
I have an X99-E WS/USB3.1 motherboard, Intel i7 6850K broadwell-e 6-core CPU, 128G DDR4 RAM. I am attempting to install 7 EVGA GeForce GTX 1080 Ti graphics cards. I have two EVGA 1600 P2 PSUs installed. Running CentOS 7. I have five of the seven graphics cards installed, in slots PCIe x16_1, x16_2, x16_3, x16_5 and x16_7. I am using and 8 graphic card mining rig. I am using Thermaltake TT Premium PCI-E x16 3.0 Black Extender Riser cable to connect the graphic cards to the motherboard. The BIOS is upgraded to 3803.
When I attempt to connect sixth card in slot x16_4 the MB will not complete a boot cycle. When I connect the sixth card in the x16_6 slot the board boots but the BIOS will not recognize the card. I have modified the BIOS setting to GEN2, set 4G Decoding enabled, but the card will still only recognize 5 cards.
BTW I do have all the power connectors on the MB connected to the PSUs.