My thanks to the authors of the 3 responses to my
query. I can dispose of one possiblity, the mb is
not overheating. The cpu cooler is a massive 
aftermarket device. In swopping out the cpus, I
removed acres of dust and I have the Asus temperature
survey utility enabled; the cpu temp reaches 51C at which
point the cooling fan speeds up to bring it down
to 49C. I will try disabling the variable fan speed
option. This morning in Normal Mode, the computer 
locked up after 17 minutes.

I haven't yet had a chance to run Malwarebytes and
Superantispyware on the computer with the problem but
I shall and report back one way or another. I have
downloaded Autoruns and will see if I can disable
the process(es) which may be causing the lockup in Normal
Mode. 

On another subject, how do I enable PCBuild so that
the answers to queries arrive at my email address?
(I am reading responses and posting this reply on
the PCBuild Archives webpage).

Thanks again.

Michael Eisenstadt
Austin Texas

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