Nvidia gtx 1080 5 card system problems

[ssmokeyy]

So I have been running this system for 3 weeks with only 4 cards no problems. I installed the 5th card yesterday and I get crashes and hard locks once I start the miner.  I tried moving it from pci slot 2 to 6 same problem. Could it be a lane problem and be a confrig problem?
Parts in this system.

windows 10 pro
msi z270 sli plus
intel g4560
8 gigs of adata memory ddr4 2666
ssd 128gb
5 gigabyte gtx 1080,
pci risers powered, 0008s model,

two seasonic plat 750watt psu's each card has its own pcie power cable, shared cable to run three pci risers. The three gpu's are on one psu that does not power the motherboard or ssd, only thing it powers is the gpu's and same risers to those gpu's.