https://manualsbrain.com/en/manuals/1561180/?page=8
Shows expansion slots and what they do depends on the cpu you are running.
Can you advise make/model of cpu? Some have 40 pcie lanes and some only 28...this determines how the slots on the motherboard are utilized. Pay attention to the * and ** notes about the expansion slots.
Looks like setting in bios of pcie slots to 8x8x8x8 would allow 3-4 gpus to run no issue. But i suspect yours are x16/x8 meaning if you only have 28 lane proc....you are out of lanes. Thus try 8x8x8x8 option and should boot. For most mining x1 is plenty.
Let me know happy to help dig into it.
I have an intel 5820k since i built this rig and i had no problem running 3x 970 GPUs at that time, i guess that's a 40 LANE CPU, anyways i might just ditch this cr@p board and entire setup and build new one, this board just seems weird !...
the best tutorial i found so far for building a ming rig is this:
https://www.youtube.com/watch?v=DR-FkpU2KfI&list=PLbB9cKIo1XI26nfh6tNUemBfVeuKpsTNy&index=169&t=239s
if a missing anything plz let me know, am getting my server boards soon (with 2x cpus each etc..) they are:
https://www.supermicro.com/products/motherboard/xeon/c600/x9dr7-ln4f.cfm
you think they will work with risers flawlessly ? am having a bad depressing start with this X99 board lol...
thanks,