Sorry to resurrect this, but I had the same problem, drivers, etc were all up to date, and I fixed it. The problem turned out to be CorePrio, that lauded program that was recommended early on in the days of the 2990wx to get windows to better use the NUMA nodes.
So if you look at your CPU usage in task manager and set it to NUMA and nodes 1 and 3 are ~70% while 0 and 2 are 100%, and you are up-to-date with windows and have CorePrio installed. Try uninstalling it.