Build:
MOBO: msi B250 PC MATE
RAM: Crucial 8GB DDR4 2133
CPU: Intel Pentium G4500 (LGA 1151)
Power Supply: EVGA Supernova 750 P2 Platinum 750Watts.
Hard Disk: SSD 128GB SanDisk SSD Plus.
GPU: 4x Gigabyte GeForce GTX 1060 6GB GV-N1060G1 ROCK-6GD
Raiser: 16x to 1x PCIe USB
OS: Windows 10 Ver 1703

Problem:
When GPU are connected to PCIe slot 2, 3 or 4 system won't boot and ZE Debug LED VGA stay solid.

Raiser and GPU works fine on PCIe slot 1, but won't start when changed to slot 2 or 3 or 4. When all the 4 GPU are connected, after several reboots, only 1 (slot 1) is recognized by Windows. When windows boots with one of the cards, it works fine and the Driver is properly loaded and operative, however it only sees one GPU, and in some occasion it recognizes two but never all four of them.

I have try all combination of PCIe slots and GPU, but nothing seems to work.

Please I need help. I really appreciate all the support you guys can provide.