the ps is modular but has only 4 gpu connector , and 5th card i have powered from molex they go on 6 pin connector at end
This is your problem
A 6 pin pci-e line can throw up to 300 watts at 12v
a 5 pin molex can only throw 5v which is a huge difference.
buy a different psu...don't use molex splitters/converters.
If you have to, use an add2psu connector.