Most desktop computers show significant performance problems when using APIC mode. The timing critical access not only X-Realtime also audio hardware is no longer guaranteed.
This one-interrupt-for-all is caused by the automatically chosen ACPI mode during installation. Normally this should be no problem, but here the IRQ sharing suffers from bad performance. The computer won't crash, and everything works, but not as good as it should. The remedy is to change from ACPI to Standard-PC mode. Here's how to do it:
One method is to repair the Windows OS using the installation CD.
Another method is through the Device Manager (Control Panel/System/Hardware), click on 'Computer', then double click on 'ACPI-PC'. Go on with 'Driver' and 'Update Driver'. Select 'Display a list of the known drivers for this device', then 'Show all hardware of this device class'. Now you can select 'Standard-PC' in the list shown in the right window. !!! Afterwards change BIOS entry !!!