Asus z370-g motherboard, it has pcie16, pcie4 and two pcie1 I connect 3 video cards: in the 16th, 4th through the riser and 1st through the riser - and when turned on, 1 long beep and 3 short, black screen. According to the documentation - "video card error". All 3 cards are working, risers are working, and 2 video cards can work simultaneously without error in any combination of connectors. But 3 cards at the same time is a mistake. What could be the reason?