I had a bunch of these modular PSUs and I never liked the way that the adapters were sorted. So if you got some knowledge with electronics and handy with tools I would order some Crimp tool, along with some pins and some AWG cables (red, yellow,black) and make your own connectors.

Some times you might not get issues with SATA but I never wanted to risk it, so I would basically use any unused modular connector and make a direct connection for my PCIe riser power. This way I never ran into anything melting.

There are videos on youtube on how to crimp all the cables. People make custom PCs and they have videos on the insturctions on Youtube to help you out. Just don't cheap out on the crimp tool or you will end up damaging the pins instead of crimping them properly.