It's cheesy and I will provide a few pics..
But basically, just set the other PSU on top of your rig and connect the always on loop connection on the 20 pin.
Install the card which needs additional power, the green arrow points to the one being powered by the case PSU. The yellow arrow is being powered by the 2nd PSU.
Route your cabling to the additional card from the extra PSU
Just showing the extra PSU on top of the case
Bridge those pins it (I had an extra male adapter with pins so I soldered a bridge)
This is just showing the two wires which get connected.. Basically the bright green with any black.
I'm just doing this till my 850 watt power supply shows up. I'm greedy, had an extra PSU and didn't want to wait to start mining.
Doge Address: DKQnN9BDspF7rwLRWR5VzsFn2JfkeTvdEA if it helps and if you're a kind person