High CPU usage due to hardware interrupts problem

High CPU usage due to hardware interrupts problem: Even with no program running, the CPU usage is 60% and the hard disk is going at full speed (indicating I/O?)

I have done all the standard scans for malware/Viruses and came up with no viruses and very little ad/spyware. I noticed high CPU usage at times when there was no program running.

I ran process explorer and found that the CPU usage due to hardware interrupt got up to about 80% and there are always at least 1,500 interrupts per scond (CSwitch Delta column). I believe this is excessive and I also believe it to be a hardware problem or possibly a driver issue. 

This turns out  ATA/IDE controllers will often revert back to PIO mode instead of Ultra-DMA.  (According to MS KB article on the problem here.)

Solution:

Check the problem by examining the controller’s Primary and Secondary IDE settings: Device Manager -> IDE ATA/ATAPI controllers -> Primary or Secondary IDE Channel -> Properties -> Advanced Settings.

Look at the Current Transfer Mode field.  If it’s “PIO” then you’ll need to uninstall the driver, reboot and let XP do its magic reinstall. 


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