Cant get my 5th card working, rig wont even start up

i have an MSI H310-F PRO motherboard, 2 x GTX1070Ti, GTX1080, GTX1060 with a 1000W platinum corsair power supply and it has been working fine for 12 months now with around 630W power draw.
i went and put in a GTX2060 and it wont even boot up now.
i have tried swapping ports its on, swapped around the risers, everything, but it will never run 5 cards. it will a maximum of 4 cards no matter what card it is, but not 5.
i have even tried a second 650W PSU connected it up and still the same issue, wont run the 5th card.
anyone know whats going on??

this forum is fuk!n useless. delete my account.

I was struggling with this problem for over a week. I tried everything . After going through every bios setting I could think of until finally on a whim I disabled the “legacy” option in the boot settings. This solved my issue and now I have 5 gpus running on this rig.