nach einem rebbot ist alles normal...
dmesg | grep -i "irq 18" liefert:
[ 5.890451] pci 0000:02:00.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[10834.872113] Broke affinity for irq 18
[10835.338208] ohci_hcd 0000:00:13.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[10835.338222] ohci_hcd 0000:00:13.1: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[10835.338297] ohci_hcd 0000:00:14.5: PCI INT C -> GSI 18 (level, low) -> IRQ 18
[10835.338790] xhci_hcd 0000:04:00.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[11135.937943] irq 18: nobody cared (try booting with the "irqpoll" option)
[11137.414746] xhci_hcd 0000:04:00.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[11137.416306] ohci_hcd 0000:00:13.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[11137.416324] ohci_hcd 0000:00:13.1: PCI INT A -> GSI 18 (level, low) -> IRQ 18
[11137.416367] ohci_hcd 0000:00:14.5: PCI INT C -> GSI 18 (level, low) -> IRQ 18