Just get the splitter, and connect the other 2 GPUs with the PSU PCI connections and you should be good. After a few hours touch the connectors and make sure nothing is too hot and melting.
May i ask you link of the molex or pcie ,
and max 2 GPU on one molex ?
I don't have any links, I bought this years ago. No max 1 GPU per molex connector. If you have 2 molex in series than make 2 GPU per 2 Molex. Keep in mind Molex is only rated for like 60Watts and depending on the GPU it might pull 30-40 Watts EACH from that molex. So if you want to be safe then just do 1 GPU per Molex and do the other 4 GPU with the PCIe splitters.
Hopefully your PSU will have enough connections, because you are trying to run 6 GPUs also which need 6 PCIe 6 (or 8 ) pin connectors already. So you will need at least 8 PCIe connectors to make it work this way.
If you do 2 GPU per 2 Molex in series, once again, depending on the GPU you are using, you might be over the limit so touch the connector and wires make sure they are not too hot.
I will buy this
https://www.amazon.com/gp/product/B0776PMH16/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
6 pin to Dual 6+2
the 6 pin to power supply sata slot ( i have 4 slot )
and the 6+2 , 2 pin away and plug 6 pin to riser
the cable review have some use it for riser
but question here , do fine use this dual ?
x1 cable 2 riser for ( x2 580 8gb )
x1 cable for 2 riser for (x2 570 8gb )
x1 cable for 2 riser ( x2 580 + 570 )
x1 cable for 2 riser ( x1 5700 + x1 1060 )
all risers will use the link i sent .6 pin to 6+2 pcie
is fine ? any issues ?