06-27-2015, 11:51 PM
That's a sufficiently large PSU, but I'm still kind of leaning towards power. Here's why:
With two cards that violate the PCI-e spec, you receive errors. With a card that adheres to the PCI-e spec, you get no errors. So I think the motherboard is intelligent enough to know that > 75W are being pulled through the PCI-e slot, and disables the slot accordingly. Disabling the slot means killing communications between the driver and the hardware, simulating an ASIC hang, leaving the driver stuck in IOWAIT and the kernel in a weird state.
With two cards that violate the PCI-e spec, you receive errors. With a card that adheres to the PCI-e spec, you get no errors. So I think the motherboard is intelligent enough to know that > 75W are being pulled through the PCI-e slot, and disables the slot accordingly. Disabling the slot means killing communications between the driver and the hardware, simulating an ASIC hang, leaving the driver stuck in IOWAIT and the kernel in a weird state.