Working fine on my Humble 4 core i7700HQ as well (Hyperthreading turned off). Have Low Latency set to On and VR pre-rendered frames set to 1 in Nvidia Control Panel.
Also check power settings there. Some have said of the new drivers kicking them down into a power save state when playing but personally I have not seen this.
- Oh and always keep an eye on SteamVR’s default.vrsettings file as updates recently have been banging
down to 4096 which sucks if you are pushing high render targets with FFR.