Power supply extention cable help

I have been previously mining on Vega 56 with an OCZ 650 watt PSU OCZ 650 watt PSU. Now I want to buy 3060.

I want to know if I can use my PSU with a Vega 56 (130 watts with tweaks and 250 watts when the OC settings crashes) and 3060(130-140 watts)

Currently, I am looking into solutions of using splitter cables. My PSU has 2×8 pin. One powering the motherboard and other along with dual molex to 8pin powering the Vega 56. I was thinking about using that dual molex to 8 pin to power the motherboard. This would free the 8 pin and on that I can use 8 pin splitter. So things would be something like this :

8pin to splitter powering Vega 56 (it needs 2 8pin) 8pin to splitter powering riser and 3060(it needs 1 8pin and one for riser) Dual molex to 8 pin to power the motherboard.

Is this configuration okay ? I don't want to upgrade my PSU

Rest specs Ryzen 5 1500 1 TB HDD 2X4GB Hynix RAM Asus prime A320 micro ATX motherboard