Continued testing with the latest linux-4.5-rc3 release. Please find attached a copy of traces from dmesg: There is a lot more debug and trace data so hopefully this will shed some light on what might be happening here. My testing remains run a series of simple benchmarks, let that run to completion and then leave the system idle away with just a few daemons running. the self detected stalls in this instance turned up after a days run time. There were NO heavy artificial computational loads on the machine. Regards, Ross Green