Why the hell are you plugging the card in x1 slot? Please read the manual of your motherboard before assembling your rig. First of all, let's make a check list:
Updated bios? Yes, then good. If no, thats the first thing you gotta do.
Set PCIe Link speed to GEN1 and then plug your card in first x16 slot, then the second card in second x16 slot, after that third card in first x1 slot just next to x16 slot and so on.
Try it and let me know your results.
maybe he mean with risers in x1 slot, he can't plug the card directly there they have no the support for that, x1 slot make sense for mining, why you said he shoudl plug there?