Finally picked up the courage to update the bios:( All went well and got a message that the bios was updated. For some reason the PC, on reboot, got stuck for ages. Rebooted few times - unplugged the mains, video cable etc. - no luck in the boot, blank screen. Tried to put Windows 10 USB stick in and it booted with a message to reinstall Windows 10!!!
Fortunately had backed up the C drive with Acronis before the bios update!
Reinstalled Win 10 and then recovered the drive with Acronis. All ok now but what a pain!
BTW the Bios version in bios is the latest now.