It turned out that I had to pair the correct set of my GPU connectors to match the splitter that was provided with the card. I have the 8 pin connector which was direct to my 3060 but the 4070 has a 16 pin connector so i had to untie some PCIe cable from my PSU to match up another 8 pin and it worked.
My PC was purpose built by one of the Gaming vendors and the wiring was neatly tied and tucked away in a PSU compartment (like they all are) so I had to dive in and pair the correct connectors.
Thanks again all for all of your help and support; I really appreciate it.
If it is truly a 800W PSU then this should be plenty of power for an 4070 Ti.
A friend runs his 4080 from a bequiet darkpower 750W PSU without any issues.