MP 1,1-5,1 dual rx580's

[crazzinezz]

Hey, I have a mac pro 5.1 2010 running OCLP 2.2.0 - SEQUOIA 15.3.1
AMD NITRO+ rx 580 powered via an external 850w power supply. I have an extra AMD NITRO+ rx 580 that I installed for a dual GPU setup.
when i run the LuxMark bench mark test, with both gpu's ticked on, my computer instantly shuts off. i'm unable to power it back up unless i disconnect the cable from the PS for a few min.

same thing happens when i try to render a video in FCPX.

Can anyone shed some light on this?

 

[reader50]

Try powering both RX580s from the external power supply.

If memory serves, the Nitro+ is an overclocked 580, drawing more power than a regular 580. And the regular RX580 is around the limits of what the on-board connectors can handle.