The best risers have a voltage regulator to ensure the voltage to the card doesn't spike. AFAIK, the only risers that have a voltage regulator are the 6-pin risers, which also use four capacitors for a more stable current flow compared to the three used by SATA or 4-pin molex risers. I use a dual PSU setup with all of the risers powered by the same PSU that powers the motherboard. The total draw for the risers and motherboard for five RX 480/580, RX 470 and one Nvidia 1080 is 360 W, so the risers are using between 45 -50 W each for the six card rig.
How is that possible?
The RX series have a 8 pin pcie connector which can deliver 150W, how can your risers burn an additional 50W.
Are you running the cards at 200W?
Btw, if risers would realy burn 50W, that would mean 300W for a 6GPU rig, which would probably burn/kill the wires or even the PSU, as PSU's dont have 300W capability on Sata/Molex rails....
I have a dual PSU setup and use EVGA P2 PSU's that have a single 12V rail and can deliver >99% of the rated power over the 12V line. The best PSU's for multi-psu rigs are dual conversion PSU's that convert the entire energy into a 12V single rail and then uses VRM to generate 5V and 3.3V. The cheaper PSU type converts using different taps in the transformer for each voltage and use the 5V line to regulate the voltage, instead of the 12V line like the dual conversion models. That causes voltage instability from not loading 5V line. The EVGA G2 and P2 series 650W and up are dual conversion models.
I use a EVGA P2 1000W with 6 PCI-E connectors for the VGA power inputs only. The total draw for 6 cards is 670 W dual mining. The main PSU that powers the motherboard, risers and SSD is a EVGA P2 750W and uses 360 W. I power the 6 PCI-E risers using four PCI-E connectors and two 6-pin pigtails.