It is simple - you switch MSI mode on and if device doesn't work you switch it back. Killer NICs have very bad reputation in my world - I have seen so many troubleshooting requests about them (and solution was namely in messing with their drivers). But again - switch-test-revert-if-something-is-wrong. PS And I just noticed that you have changed the priorities of almost all devices to High - against the advises in this thread. It is OK if you see a good difference, but that approach violates the logic of testing - one step per test. Have you changed the priority one by one with tests between? PPS You can omit the Latencymon from the screenshots, or at least show the page with details about ISRs - that`s what is affected by MSI mode tweak.