Windows – Diagnosing hardware interrupt process usage proble

dell-dimensioninterruptswindows xp

I've got a 5 year old Dell Dimension running WinXP SP3 that's really chugging along – Process Hacker (and Windows Task Manager) both report abnormally high Interrupt CPU usage. This ranges from 10-70%. I've read some about DMA vs PIO problems – are there other issues that can cause this kind of hardware interrupt spike in CPU usage? Where would one start?

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