2.) I installed the GPU 0 on my PCIe x16 slot. The other ones are connected with normal raisers. When I try to remove the GPU from the x16 Slot and connect it with a raiser to PCIe x1 the whole mining Hasrate will fluctuate from 20 - 26 MHs. And the Wattage fluctuate too. Without Undervolting settings the wattage is only 60 - 80. It should be ~ 115 watt.
Seconding farkeytron here.
I was powering risers fine with SATA until I got more than 4 cards in the rig. After that I saw similar instability so moved to PCI-E power with splitter cables. This also increased my 580 hash rates a bit.
That said, I have one Power Color 580 that runs hotter and produces stale hashes lately. I’m currently downclocking it a bit to see if I can make that stop.