"Any help would be very much appreciated."

And yet, when someone gives you a straightforward answer you complain that its not good enough.

My apologies, as I was called away and did not give a more detailed response, but in this case Google was your friend and could have given you a lot of different answers. So I will try and clarify.

As for pwr_fan - various sources say that it won't control the fan speed and its proper use is for monitoring PSU fans where supported. If you have more fans than chassis fan connectors, you could presumably use this as it should be possible to power a fan off it, however. Practically this would be preferable if you didn't want to use a molex connection specifically for fan power, but its not a replacement for a proper chassis fan supply.

You could also buy yourself a sys_fan splitter Amazon which will mean you can free up a header for use with the VGA cooler, be careful fitting that as there have been a few reports of damage to the GPU.