NeoGen I think the first set of temperature readings were false as I used Speccy and it doesn't seem to support the Ryzen 2 series of CPUs yet. There hasn't been an upgrade to it yet. The second set of readings were from HWMonitor latest version and it does support Ryzen 2s. Maybe the thermal pad thing got squashed? It was certainly hard to install the original Wraith cooler.

Anyhow it has the Noctua cooler and thermal paste now.

This evening I have replaced the PSU from an old 750W no name to a Corsair AX860. It is running NumberFields @ Home but still randomly locks up. Now I'm trying 75% CPU and 50% of CPU time in BOINC's preferences. Will see if it runs OK now.