ACPI causes 100% on one CPU-core

After building in a new motherboard (ASRock N68 C-S UCC) my system gets unusable if I boot with standard settings. top shows that the process kworker/1:1 uses 100% of the CPU. The problem doesn’t occur if I start with the bootoption acpi=off.

Here’s an extract from my /var/log/messages

Can someone help me to fight that monster called “wrong implemented ACPI”?

So why not boot with ACPI off?