Windows 8.1 display times out

[CESIL]

I have some new laptops here running Windows 8.1 and rather that wipe them and install Windows 7 I thought I would try running with the existing OS.

 

But...although I seem to have got everything working reasonably well, there is still an issue with the screen saver or something else that keeps blanking the screen after about 5 minutes!

 

I have changed all the settings I can find and still the display times out...has anybody here had or solved this problem?

 

I have run out of places to look for the mystery 5 minute setting so any suggestions will be gratefully appreciated