MacPro / Sapphire RX 580 setup

Discussion in 'Mac Pro' started by angelinho, Dec 14, 2018.


Is it safe?

  1. Yes.

  2. No, but there's another way.

    0 vote(s)
  3. No, return the card.

    0 vote(s)
  1. angelinho macrumors newbie

    Dec 14, 2018
    Hi all, I own a macpro (2012) currently running high sierra with the default Radeon HD 5770 (i think that's the card)

    I ordered the Sapphire NITRO+ RX 580 Special Edition and it requires a 8 pin and 6 pin power connectors.

    I did my research and the few people who posted about this special edition card mentioned they ran it using a 2 mini 6 pin to 8 pin connector and leaving the 6 pin on the video card unused

    I was planning on using a dual mini 6 pin to 8 pin and a sata to 6 pin so I can power the GPU

    Something that's bothering me is that the dual mini 6 pin to 8 pin sounds very legit from all i'm reading I've done however the sata to 6 pin is like 50/50 a lot of people are claiming fire hazard! While the other half are not sweating about it.

    Here's my logic at play:

    the graphic card will draw 75w from the PCI slot, 150w from the dual mini 6 pin to 8 pin, and 50w from the sata to 6 pin

    The math is 75w+150w+50w = 275w

    which according to this link, it should not draw more than 237.4w "torturing" the card. Now the card referenced is not the special edition but rather another nitro+ version and I am no electrician expert.

    BTW, I won't be overclocking this.

    Thoughts on this? I won't be able to return the graphic card if i open the box so your input would be greatly appreciated. cheers
  2. crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
    If I’m not mistaken, you only need the 8 pin connection on the GPU. I believe the 6-pin connection is optional, and card will automatically avoid any attempt to draw my power when that connection is omitted.

    However, you really need to do so some searching and then reading on your own. The answers are already posted and fairly recently. Please look for the answer before making a new thread.
  3. angelinho thread starter macrumors newbie

    Dec 14, 2018
    Thanks for your input, and believe me I’ve done a lot of reading but like I said the SATA TO 6 pin is my main concern, so I wanted to hear peoples thoughts on this setup there’s only a few vague posts on this particular graphics card with a Mac Pro

    Do you think I should just leave the 8 pin in and not use the sata to 6 pin at all? Use both? Or what’s your recommendation?
  4. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    The 6pin is optional, not required.

    Just leave that unconnected, then nothing need to be fixed.

    And your "power draw maths" is completely base on what your want, but not base on the card's behaviour. TBH, that calculation won't work.

    Why the card "will" draw all 75W from the slot, all 150W from the 8pin, but automatically limit itself to draw only 50W from the 6pin. The card has no idea what the 6pin is connected to. As long as it's a 6pin itself, it can be programmed to draw up to 75W. Same logic applicable to the slot connector and the 8pin.

    Regardless the TDP, as long as there is a 8pin, the 8pin itself may draw up to 150W. As long as there is a 6pin, it can draw up to 75W.

    e.g. For a 225W GPU, it can

    1) draw 75W from slot, 75W from 8pin, 75W from 6pin

    2) draw 50W from slot, 125W from 8pin, 50W from 6pin

    3) 25W from slot, 150W from 8pin, 50W from 6pin


    There are unlimited combination, all of them are valid. There is no reason why the card "will" draw all 75W from slot, all 150W from 8pin, but only 50W from 6pin.

    Even the card only draw 237.4W. It may draw 67.4W from slot, 70W from 6pin, and 100W from the 8pin. In this case, you may kill the SATA port by connecting it to a 6pin demand.

    Anyway, check your graphic card's manual. The 6pin should be optional (officially). As long as the manual says that, leave it unconnected, and only use the 8pin + slot to power the card is the way to go.
  5. angelinho thread starter macrumors newbie

    Dec 14, 2018
    Good stuff man, I couldn’t find if the 6pin is optional on the special edition. The power consumption says <250w

    Do you know of a way to tell the consumption behavior of each port? Or if you could regulate the power consumption of each port using software? (Doubt it, just asking)
  6. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    Sapphire says it's optional on the official webpage

    Screenshot 2018-12-16 at 1.14.41 AM.png
  7. angelinho thread starter macrumors newbie

    Dec 14, 2018

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