Ok sound like your setup is ok,
How do you power the 8+6 pins gpu power input ? 1 cable with a Y separation ? 2 cables ?
Have you tried to use for example 60% powerlevel ? does the issue happen before mining or at mining start ?
Your psu should be enough, with this configuration you should reach about 650w at wall.
Maybe a bad riser, but it seems odd it crash the rig completly. Are you using gen1 pci in motherboard bios ?
Answered in order:
My PSU has enough individual outputs on it that I run a separate cable from the PSU to each GPU. I felt this would be the safest way to avoid voltage drop despite the snaggle of cables. I'm getting tempted to see what voltage each one is seeing.
At this point, I can't even get past the Windows login screen with 4 GPUs on let alone changing my undervoltage levels
I sure hope so! I picked the 1000W unit as I thought it would be enough to max out the MB with PCI slots. The highest draw I've seen at 72% is roughly 575W at the wall using a Kil-o-watt meter.
I don't believe so but I'm sure I can check. The MB comes with 1 x PCIe 2.0 x16, 5 x PCIe 2.0 x1 I'd have to assume it was stock 2.0. Hell I didn't even know that was a selectable thing, figured it was a hardware protocol.