crash – Windows 10 PC crashes following Kernel-Power Event ID 125

Every now and then (perhaps once a day) my PC running Windows 10 randomly crashes to a black screen. When this happens, the CPU fan ramps up to full speed until I manually reboot. This doesn’t seem to be connected to what the machine is being used for – it’s happened running games, but also idle on the desktop. Event Viewer shows the cause is always a Kernel-Power Event ID 125, like this:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
   <System>
      <Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331c3b3a-2005-44c2-ac5e-77220c37d6b4}" />
      <EventID>125</EventID>
      <Version>4</Version>
      <Level>4</Level>
      <Task>86</Task>
      <Opcode>0</Opcode>
      <Keywords>0x8000000000000020</Keywords>
      <TimeCreated SystemTime="2021-08-30T18:06:09.7493189Z" />
      <EventRecordID>26724</EventRecordID>
      <Correlation />
      <Execution ProcessID="4" ThreadID="404" />
      <Channel>System</Channel>
      <Computer>DESKTOP-9UFBQA3</Computer>
      <Security UserID="S-1-5-18" />
   </System>
   <EventData>
      <Data Name="ThermalZoneDeviceInstanceLength">9</Data>
      <Data Name="ThermalZoneDeviceInstance">_TZ.TZ10</Data>
      <Data Name="_PSV">290</Data>
      <Data Name="_TC1">0</Data>
      <Data Name="_TC2">0</Data>
      <Data Name="_TSP">1000</Data>
      <Data Name="_AC0">0</Data>
      <Data Name="_AC1">0</Data>
      <Data Name="_AC2">0</Data>
      <Data Name="_AC3">0</Data>
      <Data Name="_AC4">0</Data>
      <Data Name="_AC5">0</Data>
      <Data Name="_AC6">0</Data>
      <Data Name="_AC7">0</Data>
      <Data Name="_AC8">0</Data>
      <Data Name="_AC9">0</Data>
      <Data Name="_CRT">294</Data>
      <Data Name="_HOT">293</Data>
      <Data Name="MinimumThrottle">0</Data>
      <Data Name="_CR3">0</Data>
      <Data Name="OverThrottleThreshold">0</Data>
      <Data Name="DescriptionLength">0</Data>
      <Data Name="Description" />
      <Data Name="_TZP">10</Data>
   </EventData>
</Event>

To me, this looks like the critical temperature was suddenly set to 294K (21°C) so the system failed, because it was obviously hotter than that. But perhaps I’m reading it wrong.

Because I thought it was a temperature issue I have resat my CPU and reapplied thermal paste. I’ve checked its running temperatures which tend to be in the 30-50°C range. I’ve made sure all drivers and software are up to date. Now I’m running out of ideas – anyone know what the problem might be? I can provide more info if needed.