Latitude E6430 ATG - High DPCs in Windows 8 x64

I recently got an E6430 ATG. It came with Windows 7 Ultimate x64 but I wiped the hard drive and installed Windows 8 Pro x64. I have not installed any Dell drivers. Windows 8 detected the touchscreen, the speakers, usb, etc and everything just worked so I figured why mess with it. I noticed today in Process Explorer that the laptop had about 20% DPC usage continuously (I checked periodically over half an hour and it didn't change). I used LatencyMon which said the biggest offender is ACPI.sys.

After all that I put the computer to sleep and then immediately woke it up again and the DPC usage had stopped. However I plugged in a usb mouse and the DPCs started again. I disconnected the usb mouse but the DPCs didn't stop. I don't know what happened, maybe it was a coincidence.

Is there anyone else here who's using Process Explorer in Windows 8 Pro x64 and keeps tabs on their CPU/DPC usage? I would be interested to hear similar experiences, any theories, etc. This thing is brand new.

 

This was solved months ago but I forgot to give an update. The issue turned out to be related to Intel's 82579LM Gigabit Ethernet adapter. I was able to get rid of the DPCs by disabling in the adapter's Power Management tab the option 'Allow this device to wake the computer' or 'Allow the computer to turn off this device to save power'. I don't remember which but I think it was the first one. I was also able to get the DPCs to reappear by enabling those same option(s). Thanks to mrhandy from the E6430 Owners Thread for the clue about the ethernet card:

I didn't do any of that. Although Microsoft did have a "new" ethernet adapter driver listed for me (the actual driver is from 2012) on Windows Update in August (I can't remember if it was optional) and I installed it after I fixed the issue with the power management settings but everything is still fine. So maybe if you are having the same DPC issue try first what I said with the power management then if that doesn't work check your Windows Update for the ethernet driver.

The driver I received from Windows Update and am using currently is Intel, 10/31/2012, 12.2.45.5031, e1c63x64.sys. For the last two months I've only had 'Allow this device to wake the computer' disabled. Whether that's necessary or not anymore I don't know. I've not seen the issue since and I have Process Explorer running in the background to always show in the systray and I've used the computer for several hours a day every day so if there was rogue DPC I would have noticed the icon change color.

If anyone else has more detailed information on the root cause please post it here, but for now I'm almost certain it was the ethernet card. Thanks