Hello, using Windows 8 on a HP z420 with GTX680 GFX. With the help of this Thread I was able to identify which Process filles up one of my CPU Cores with 100% of interrupt handling. It's the ACPI.sys - but now I don't know how to investigate further and find our why ACPI.sys is eating up one Core of my System ... Maybe someone here can help me on this? (And what Information do you need for helping me out here?) Thank you, bye from snowy Austria Andreas Schnederle-Wagner