Interrupts spikes to 80% of CPU

PIO to DMA was the problem. Amazing solution! Thank you so much.  This was causing so many headaches.  I originally noticed the System process (220K [no .exe]) was floating high, then downloaded Process Explorer to get more insight on this.  Happy computing once again!

Thanks to ProcessExplorer and these posts I was able to identify the problem as the PIO mode on the IDE controller of a laptop that was running like a snail.  I thought it odd the other day when looking for suspicious processes that the interrupts were occupying most of the CPU cycles.  A quick search in the forum here revealed the answer.  The Primary IDE channel was set to PIO mode, even though the preference was set to DMA.  Uninstalled the Primary IDE channel from Dvc. Mgr., restarted twice, and it's running much faster now with the Primary IDE channel now running in DMA 5 mode.

The laptop in question is a Dell Inspiron E1505 running WinXP SP3.  It was infected with several viruses when brought to me.  After scanning and removing infections with Malwarebytes & AVG, it was still running like molasses though.  The IDE tip here did the trick.

Thanks!

That is indeed what it was, as I learned from another thread on these forums.  Thanks for all the help.

I seem to have the same, if not very similar problem.  It appears to be IO based (when unrarring or copying files, 4th core of CPU gets pegged).  I updated all of the windows(XP SP3)/audio(realtekHD)/video(geforce 8800GT) drivers and it made no difference, in fact it seems to have gotten worse.  My system also takes a good 4 minutes or so to boot, and it used to be ~30 seconds.  IO intensive processes seem to take down the 4th core most, with the others following in lesser severity.

This is a screenshot of the onset of copying a file (~750 MB) from one drive to another.

Any thoughts, or are there any recommendations?  I uninstalled the Realtek HD audio codecs and it made no noticeable difference (didn't restart yet, if that makes a difference).

Hey.

Well I cant believe I fixed it. I just had to disable UAA bus driver for High Def Audio @ System Devices. Pretty random to be honest. I coul've reinstalled win dozens of times without a solution. Damn.. thank god I found that.