Dual SATA to 8 pin viability

[ThisIsntGood]

I'm thinking about getting a Vega 56, and I already have a 6-8 pin adapter for the first 8 pin. I'm asking if I could use a 2x SATA - 8 pin adapter to supply the additional power, but I'm not sure if the SATA rails are strong enough. I have the 600w PSU

[SDH]

The ATX standard from a PCIe auxiliary power supply cable is 75W at 12VDC, and the ATX standard for a PCIe x16 video card slot is another 75W coming up from below.  HP engineering is above ATX standards.... the Z420 slot is good for 75W, but the cable is rated to 18A at 12VDC.  That is, P = I x V... P = 18A x 12VDC ... power = wattage = 216 watts via the cable.

The card you noted specs out at wanting 210W "typical", and the PSU recommendations from ATI for the workstation is 650W.  SSDs draw less power than the HDDs the Z420 was engineered for, and with that 18A current capacity over the HP supplemental PCIe power cable you would appear to be fine unless you're drawing significant power elsewhere.  Breathing room is built in.

On this forum we have posted about the special HP cable adapters for their power supplies..... 1 HP PCIe 6-pin supplemental cable to 8-pin adapter, for example.  You don't want to use a cheap generic one... they are not all the same.   I'd find one made by HP for this purpose.  They know their engineering and built the adapter to those specifications.