I have a Q6600 based system with a Gigabyte motherboard P35-DS3p that has DPC latency problems. By running LatencyMon, it was possible to see that it seems to be caused by the "tcpip.sys" driver. After disabling everything I could, it is still at the top of the DPC count in the driver section, after the LatencyMon driver itself. On LatencyMon's main screen everything is in the green except hardpage fault resolution time which is off the chart. This system does not go on the internet or even use LAN. Network cards are disabled, network drivers are disabled, but the system does not let me turn tcpip.sys off in device manager, which returns a "control not valid for this service" error. Am I right in thinking I shouldn't even need tcpip? It would be nice to use the system for a DAW all the time, but it's just to unreliable. To record something, I have to use an old Pentium 4 HP laptop which works great for this purpose; it can record 16 tracks at a time with no problems. Any help will be appreciated.

Finally was able to disable tcpip.sys in Safe mode. LatencyMon "highest reported hard pagefault resolution time" still a bit in red, but am now getting the "system suitable for realtime audio" notice. I'm keeping my fingers crossed that all will be good now. Cheers, Dan

It will always be on the list of top offenders if you have any kind of network running (internet, etc).
 
However I've found at times reseting it back to defaults can cure spikes over and above what should be expected.
 
Copy and paste the text below and save it as;
 
Ipreset.bat
 
(make sure Notepad doesn't append .txt at the end of the file when you save it.)
 
You can then double click it to reset your TCP IP and the Winsock catalog to their defaults.  It will pause between each instruction prompting you to hit space. Reboot when complete and test again.
 
Keep the batch file handy as you may need it again some time in the future.
 

 ipconfig /release 
     pause 
     ipconfig /renew 
     pause 
     netsh winsock reset catalog 
     pause 
     netsh int ip reset reset.log 
     pause 

 
Also note whilst LatencyMon does a pretty good at finding likely suspects DPC latency checker is more reliable at showing DPC activity.  Hard faults or Page faults are not too much of a concern here as they are just indications of processes accessing the disks pagefile rather than your hardware RAM, as such they are not indicating your machine is broken in any way.

OK thanks, Jonbouy. Good info there; handy little bat file to have. I wasn't sure if hardpage faults were of concern or not; it's good to know that they are not of the utmost concern. DPC latency checker now maxes out at 86uSec, another good indication. Before, it would stay in the green with a good spike every couple of minutes. But the bottom line is Sonar would just hang completely for a few seconds now and then. I tried recording 16 tracks at a time, and it works!!! Things are looking up. I also ordered an SSD drive and win7 for this computer for when I install X2. It should be really good when all that is installed.