Posts: 17
Member Since: ‎12-12-2008
Message 1 of 26 (20,462 Views)

High CPU utilization due to hardware interrupts

I’m seeing high CPU utilization on one core in my dual core system, it always core 1.  It runs at 75-80 percent utilization.  After installing the Process Explorer from the MS website (which is really coo), I found that it is due to a very high number of hardware interrupts on that core.  The other core seems to be running fine (which is good for me).  The high utilization from interrupts does not stop.  Each time I reboot the system, it will go away for a while, but always returns.  It used to take a few days to return, but now seems to return within a few hours.

System: a6257c (Pavilion)
Model: GN709AA-ABA
Memory: 3 GB (3 1 GB SIMMs, I added a 1 GB SIMM to boost the memory to 3 GB)
CPU: Intel Core 2 Duo, 2.2 GHz
No other H/W has been changed on the system
OS: Vista Home Premium (32 bit) with SP1 and other current Windows updates.
Printers: I do not have any printers installed on it.  I do not have any network printers installed on it.

I’ve spent quite a lot of time researching this issue from many different sites.  The high hardware interrupts causing high CPU utilization is not uncommon, but none of the other site had solutions or their solutions did not solve the problem I’m having.

Things I’ve done.  I went through and restarted just about every service I could.  I went through and shutdown every service I could.  I uninstalled the driver for the CD-ROM/DVD (as suggested at other sites).  I am not running out of memory and constantly swapping (as happened to a user at another site).  This issue predates my addition of the 1 GB SIMM to boost memory to 3 GB, from 2 GB.  I’ve gone through the Device Manager and looked for updates to all the devices (only one needed update).  I’ve gone through the Device Managed to actually verify with my eyes that the listed current device drivers listed on the HP web site are indeed the ones installed on my system.  The only thing I’ve not done yet is upgrade the BIOS.  My reason for not doing that yet is described here:  I’ve opened the case and vacuumed it out.  I’ve not been able to actually be looking at it when the CPU load goes up, so I don’t know what changed at that point in time to cause it.

There are only 2 things I can think of right now that might help.  1) The BIOS upgrade.  2) Add another 1 GB SIMM for memory.  I know that adding the memory will not give 32 bit Vista much more, but it will mean that the memory is in pairs.  I’ve doubtful of either of those and would appreciate some more informed suggestions.

This is a problem that has been bothering me for a while.  I’d originally blamed it on some of the Media Center stuff, but now believe that was wrong.
Distinguished Professor
Posts: 2,330
Member Since: ‎11-17-2008
Message 2 of 26 (20,445 Views)

Re: High CPU utilization due to hardware interrupts

Well... to me, it sounds what your PC is experiencing is perfectly normal. In a dual core system, the OS or most apps don't share the cores equally. Only certain software designed to take advantage of multiple threads will task the other virtual processor.


HW interrupts are a normal part of the work. If the processor is under load, it will get more interrupts. You've probably just got a lot of software starting up.


Things you can do...


Prevent software from starting.

Fully close the Windows sidebar.

Disable Aero (even if it is temporary)

Fully Exit HP Total Care Advisor and other non-essential applications.

Disconnect the network cable and stop virus scanning.

Let it sit for an hour and see if you still have the "problem".


Read this... good stuff... Increasing System Performance Without Adding Memory in Windows Vista



... an HP employee expressing his own opinion.
Please post rather than send me a Message. It's good for the community and I might not be able to get back quickly. - Thank you.
Posts: 17
Member Since: ‎12-12-2008
Message 3 of 26 (20,437 Views)

Re: High CPU utilization due to hardware interrupts

Thanks for the suggestions, but they miss the mark.  At startup, all is normal.  There is a CPU load for applications starting up.  After that, the computer settles into a “normal” CPU utilization, about 4-6% (pretty equally distributed on both cores).  At some point, things go wrong and the time varies from 30 minutes to a few days.   Core 2 is fine, but Core 1 is hit by an unrelenting storm of hardware interrupts.  It never stops, hours or days, even when the computer is otherwise idle.  This is not normal startup behavior.  Core 1 becomes unusable.  I’ve gone through the process of shutting down applications and services (which I described in the original post).  I’ve updated drivers, reinstalled drivers, blaa, blaa, blaa. The only thing that seems to stop it is a reboot.  That only stops it temporarily.

Regents Professor
Posts: 5,278
Member Since: ‎12-02-2008
Message 4 of 26 (20,430 Views)

Re: High CPU utilization due to hardware interrupts

Have you tried to re-install Vista?

Please mark the post that solves your issue as "Accept as Solution".
If my answer was helpful click the “Thumbs Up" on the left to say “Thanks”!
I am not a HP employee.
Posts: 17
Member Since: ‎12-12-2008
Message 5 of 26 (20,344 Views)

Re: High CPU utilization due to hardware interrupts

Thanks and ouch.  Just the thought of that makes my teeth hurt.  I’ve had the system for a while, so I’d have a couple dozen apps to reinstall, accounts to recreate, and, of course, a lot of data to backup and restore.  At that point, I have to wonder what is worse, the sickness or the (possible) cure.  However, it may come down to that.

For a while, I thought I had it beaten.  It went 4 days without a reoccurrence, then whamo, 3 times in 1 day.  The only way to free up that CPU is to reboot the system.  That is a real pain since this system is my central desktop.

I did manage to watch it happen (or nearly so) a couple of times this week.  I did not see anything different that is causing the never ending H/W interrupt storm.

Posts: 17
Member Since: ‎12-12-2008
Message 6 of 26 (19,982 Views)

Re: High CPU utilization due to hardware interrupts

I've had to reboot twice today because core 1 was busy with the “hardware interrupts.” Maybe this time it will hold up a bit longer. My big concern is that something is nearing failure and this is how it is showing it. Am I about to drop my disk drive, video card, motherboard, ...? If given a choice (as if the computer will ask me), I could do without the CD/DVD.
Posts: 2,491
Member Since: ‎12-09-2008
Message 7 of 26 (19,966 Views)

Re: High CPU utilization due to hardware interrupts

Try updating the BIOs.If you have not done so.There are some processor fixes in the update.If you don't feel at ease doing this you can contact HP chat and ask them to walk you through it.





Posts: 17
Member Since: ‎12-12-2008
Message 8 of 26 (19,891 Views)

Re: High CPU utilization due to hardware interrupts

I applied the BIOS upgrade.  Unfortunately, it did not solve the problem.  Within a few hours, the CPU load on core 1 was back to 90%, due to mysterious H/W interrupts.  A reboot will give me back both cores, but that is not very convenient.  I guess I’ll detach the CD/DVD and see if that helps.
Posts: 2,491
Member Since: ‎12-09-2008
Message 9 of 26 (19,882 Views)

Re: High CPU utilization due to hardware interrupts

I had one do this and the processor was bad.It would run 98-100% load just sitting.That was with me turning off all services on reboot.I would try the cd/dvd rom and if it does not solve the issue,mail it in for warranty.
Top Student
Posts: 5
Member Since: ‎01-19-2009
Message 10 of 26 (19,689 Views)

Re: High CPU utilization due to hardware interrupts

Hello, and greetings from Finland!


I am also suffering these exactly the same problems like rjc does, alltough I'm running on a 'bit different machine: HP Desktop PC (Pavilion). So far nothing has helped, and I've also tried pretty much everything I've been able to. I asked some help on two Finnish forums, but haven't been able to get any conclusive help so far... There aren't any critical errors on event logs, and I have tested hard drive and other components. And this PC has been tested on HP warranty service here in Finland, but they didn't find anything... So I did reset the system back to the original factory settings, 13 or 14 days later same problem occurred...


So my story is exatly the same as rjc, including every single efford to solve this problem. All the softwares (I don't have much of them installed) have the latest upgrades, so does all the drivers and BIOS. No outside devices installed. Currently I don't even have any antivirus or firewall installed, all I have is A-Link RR 24(i) with SPI firewall + NAT and Windows Vista firewall, even the Windows Defender is disabled (including its service).


Just like rjc described, this problem occurres completely random interwalls, and there's absolutely nothing that seems to trigger it! And on my PC this is a little bigger problem since CPU has only one core. But there is a small upside which I came to notice by happy accident: I don't have to reboot the system when this interrupts-problem happens, all I have to do is activate the sleep mode and then wake the system back up again, after that the CPU is idle, CPU usage is 0-2%...


I did call to HP support quite a few times and they don't have a clue what's causing this, they just recommented to try reseting the system back to the factory state, again, I've done it twice allready and it wasn't anywere helpful!


Like rjc, I've also upgrated the memory up about six months ago, I have 2 GB of RAM installed (motherboad doesn't support any more), but these broblems appeared even before that, alltough I didn't recognize it back then until couple of months ago with help I got on Afterdawn forum (someone recommented to try Process Explorer)...


Then some days ago I found this:



"My resolution


My IS guys at work ran my machine through a barrage of test looking for worms, viruses, missing dll, bad drivers. They found nothing, no malware, nothing bad. They tested the hardware no hardware issue. One of the guys had a hunch. He knew my system ran Home Edition and swapped out the OS for XP Pro. The interrupts went away and my CPU usage went down to 0-2%. He believes that the 64 bit processor was not compatible with XP Home Edition.


In a conversation I had with HP support, the support guy said that they modified the Home Edition alittle but guaranteed that the system was fine. I couldn't do a clean load of Home Edition to verify because...HP doesn't send recovery disks and OS any more. They partition a part of the disk drive to hold the original image of the system. I did try to load from the image and got the same High CPU and interrupt counts. They only way was to get a copy of XP Pro and reformat the disk. Now its running exceptionally well. I have Microsoft Live One Care as my antivirus-security program instead of Symantec."

I don't know what to think about that, but this can't be the case on Vista, or is it?


So anyway, this is my story. I'm still monitoring the system and try to call HP support again some day and see if they have any solution for this. But rjc, if this helps, you're not alone with this problem :smileyhappy:




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