Computer starts at a specific time

My desk top computer starts automatically every evening at 7.00 p.m exactly.
All information gleaned from the internet advising bios settings, power management, scheduled tasks and 'wake up' signals have all failed to resolve the problem.
Any further advice?
No virus appears present. I am aware programs are available that create start and stop times, but these are not installed.
thank you
Russ B

Looks like you covered all the bases ! If it recently started happening, Windows restore to prior time might solve it.

A single clean scan does not necessarily guarantee infection free.
What AV do you run ? I usually recommend running other scans like rootkitrevealer, Malwarebytes Antimalware, for two.

Also, something in temporary folder might trigger something to kick off !