Built up my first mining rig. TRYING to run 7 RX 580s but the only power supplies I could find were two Corsair 750w units. So I have them set up running dual, but the problem is each power supply only has two 8 pin connectors. So right now I can only run two GPU's per power supply 
My AMD Radeon cards require both an 8 pin and a 6 pin connection to work. Yeahhh... so obviously this is not an ideal situation but it's what I've got.
The four cards are mining great but I have 3 other GPU's still sitting in the box. I'd really prefer not to have to spend another $360 on a new power supply since I'm past the cut off to return the two Corsairs.
In addition to the two 8 pin connectors, there six 6 pin connectors on the PSU's. I found this cable on amazon:
6 Pin male to Dual 2x 8 Pin (6+2) male PCI Express Power Adapter Cable for Graphics Video Card 24-inch
https://www.amazon.com/COMeap-Express-Adapter-Graphics-24-inch/dp/B076YXS6KL
And it appears the 6 pin would connect into the PSU and the other two ends 6+2 and the 6 pin would connect into the video cards.
Is this cable safe to run without worrying about starting a fire? The GPU's are drawing 185w each
My AMD Radeon cards require both an 8 pin and a 6 pin connection to work. Yeahhh... so obviously this is not an ideal situation but it's what I've got.
The four cards are mining great but I have 3 other GPU's still sitting in the box. I'd really prefer not to have to spend another $360 on a new power supply since I'm past the cut off to return the two Corsairs.
In addition to the two 8 pin connectors, there six 6 pin connectors on the PSU's. I found this cable on amazon:
6 Pin male to Dual 2x 8 Pin (6+2) male PCI Express Power Adapter Cable for Graphics Video Card 24-inch
https://www.amazon.com/COMeap-Express-Adapter-Graphics-24-inch/dp/B076YXS6KL
And it appears the 6 pin would connect into the PSU and the other two ends 6+2 and the 6 pin would connect into the video cards.
Is this cable safe to run without worrying about starting a fire? The GPU's are drawing 185w each
Generally, you don't want to have the possibility of any single line of PCIe power connectors carrying a load greater than 2x 8-pin connectors. 1x 8-pin and 2x 6-pin should be fine, 3x 6-pin, etc. However, it's also difficult to know how a given card distributes the power it requires between the PCIe slot and one or more onboard power connectors. For example, with splitters, you *might* be fine powering more than 4 risers off of one PSU line of PCIe power connectors, but I still wouldn't recommend it.
Lastly, if you intend to run all of the cards at the full 185W TDP, you're going to have a problem with only 2x 750W PSUs.