Fresh XP Pro+SP2 install, System =100% cpu, DPCs are huge!
Posted on 2004-10-09
I have been asked to repair a Windows XP computer with the general symptom of performing very slowly when doing simple operations. The Task Manager showed the System process consuming a large amount of CPU, eg: >85% sustained - even when the computer is doing no work on behalf of the user. This machine is used for dictating into MS Word via Dragon Naturally Speaking, and was very slow and sluggish (10 - 45 second delay) and inaccurate (because the app seemed to eventually give up on attempting to translate speech into text).
I have low level reformatted the hard drive, reinstalled the OS with Win XP Pro and applied SP2. Sometime after installing Mozilla, I happened to run the Task Manager and saw that it is (still) running at high levels of cpu consumption.
One fyi is that the machine has a 250G disk, but install only showed 137G. Apparently this is true for XP < SP1, because XP followed the letter of the standard rather than the actual bitwidth of the disk cable.
Here's what I've done so far:
I have scratched my head, in true WTF fashion.
I have removed all cards from the backplane, on the outside chance that one of them is a culprit. Doing this did not vary the symptom.
I have applied all of the drivers which came with the mobo, a K7SEM from Elite.
I have not reflashed the BIOS.
I have downloaded and run all of the freely downloadable tools from sysinternals.com. AutoRuns shows 3 reasonable things at startup. FileMon shows occasional bursts, but they are few. ProcessMon shows: system ide process: 3%, Interrupts: 31% (Hardware interrupts), DPCs: 46% (Deferred Procedure Calls), System: 21%. (open question: How can I learn more about what is generating these interrupts and DPCs?). RegMon shows there are occasional flurries of activity in the registry when I move a window, but nothing tied to cpu utilization. TcpView shows a few posted listens, and nothing strange. All others show benign activity.
I have posted an email to the Elite MoBo website describing the problem. No response yet.
The HardwareManager was empty but is now populated. start->control panel->system -> Hardware Tab -> Device Manager. The list is empty. (researched this on EE, refd to an MSFT support article on enabling PnP, which did not vary the symptom). However, when I ran compmgmt.msc from the command prompt, the list in the device manager was *not* empty and looked properly populated. Also, when I just redisplayed the Device Manager via control panel -> system, the list is now populated. This is a variation.
I have researched through the first several pages of results from EE when searching for some combination of high cpu consumption and the system process. Some suspect infections. This is a fresh install + sp2, but I have scanned the computer using PC-Cillin and it found nothing.
WindowsUpdate was run and the dl options chosen are: GDI+ detection tool, .NET framework, NIC update, AUdio Driver update, Video update. (all core/ crucial things, any of which can cause this high cpu consumption). Installing. Done. No change.
Researched into what are DPCs, and what could be causing so many interrupts to cause the percentages to be, shown using ProcessExplorer, 44% and 31%. Btw: PE shows the System process is 20% utilzation.
Is there a way to cause the TaskMgr to show unreliable consumption numbers, or for it to cause high consumption on it's own?
*Any* thoughts on this?