Review on Enhancing Your Power Supply: Add2PSU Multiple Adapter and Daisy Chain Connector by Genetek Electric by Ismael Hennigan

I bought one like this, not the PSU cable splitters that you sometimes hear horror stories about (light up), and also because there were a lot of positive reviews for this one, although the price is a little higher. I've had this on a 6x 1080 Ti setup with 2850w power supplies for about 2-3 weeks and haven't had any issues. The power supply connected to this adapter turns on a fraction of a second after the main power supply, and when I need to shut it down for maintenance, the power supply on this adapter also turns off a split second after the main power supply. This is solid rock. My only minor complaint is that like the PCI-E riser, it comes without the foam backing and also without screws. So if you want to mount this to your rig, you'll need to pick up some small wood or metal screws.