I think I did. Use LatencyMon to find the service, go to the service tab in task manager to find the service, right click and select go to process. It will take you to the process tab and then you can set the affinity on that process. Yes, many are called svchost.exe and have different parameters, so that why you need to go to the service tab and then right click for go to process. As regards wdf0001.sys, tricky, I couldn't locate it either by the method described, so maybe a process of elimination to find which service is causing the problem. See if you can find out more about wdf0001.sys, windows device foundation, it's a driver. See if you can find what service it is attached too or select half of the services (that you haven't already and set the affinity) put them on one set of cores and see if that makes a difference. If not, try the other half. Then try half of that or the other half and your find which one it is (like a binary search).