2013 Mac Pro fan stuck on high

Recently had a power outage. When the power came back on the Mac Pro turned itself on immediately and now the fan runs at full speed and the Mac is very slow. Tried doing SMC reset by removing the power cable as suggested but to no effect. The computer turns itself on again.

Is there anything I can do re software... reinstall OS... wipe the drive and start again?

Getting to the point where I’ll try just about anything. thanks Pete