Powering 1080ti in 2010 5.1 Mac Pro?

Discussion in 'Mac Pro' started by spiteyourface, Jul 1, 2018.

  1. spiteyourface macrumors newbie

    Joined:
    Jun 23, 2018
    #1
    Hi,
    I've searched and found answers to similar queries to mine, but 'similar' hasn't helped me so apologies for any repetition.

    I've bought an Nvidia GTX 108ti for use in a Mid 2010 5,1 Mac Pro.

    The card has/requires 1x 8-pin and 1x 6-pin.

    The only cables I have immediately present and which came with the card are a dual 6-pin to single 8-pin adapter, and a dual molex to single 6-pin adapter (similar to this) with large molex connections that don't seem to relate to anything in the Mac.

    So with the available cables I can only plug the native mini-to-6-pins into the dual 8-pin adapter, which uses up the only two existing connection points for the 8-pin connection, and leaves nothing for the 6-pin.

    Basically, how do I (best/optimally) connect this 6-pin + 8-pin card to the Mac Pro?

    Can/should I use the available adapter to connect the 8-pin to the twin 6-pins, then use one of the empty Sata slots with a Sata-to-6-pin for the 6-pin (which I'll have to purchase)?

    Or would it be more optimal to use Sata slots for each, ie 1x Sata-to-6-pin and 1x Sata-to-8-pin if I want the best results from the card as well as simply powering it?

    Or something else?

    Sorry to sound like a noob but I'm a noob.
     
  2. h9826790 macrumors G5

    h9826790

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    #2
    If your card is the 1080Ti FE, or any non OC reference card. Using EVGA power link is one of the easiest way to power it with just the two mini 6pins.

    HOWEVER, technically, that's way over the mini 6pin's official limit. It can work flawlessly practically, but only if you willing the take the risk.

    A mathematically safe way is to power the 6pin by TWO SATA ports. And the 8pin by TWO mini 6pins. However, it's only good when considering the average power draw from the graphic card. And there is no info about if the SATA ports can handle the power spike. But so far, never heard anyone burn any port with this method, so should be very very safe.

    If you want a more permanent solution, Pixlas mod is the way to go.
     
  3. spiteyourface thread starter macrumors newbie

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    Jun 23, 2018
    #3
    Thanks.

    It's not Founders Edition, just this off-the-shelf model. Not sure what OC reference means? Does that mean I can't use that powerlink thing to run it off the two mini6pins?

    That Powerlink product is ambiguous. Are both the inward and outward sets of connectors fully adjustable and coming with all components, because most pictures show it with two 8pin plugs on the external?

    So which are you saying is actually preferable performance wise, the Powerlink, or the twin-sata-to-6pin method? I presently have precisely two Sata ports empty but in the future will likely just have the one.

    The Pixlas mod looks a touch ambitious for me right now, maybe at a later date...
     
  4. h9826790 macrumors G5

    h9826790

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    #4
    There should be no performance difference no matter how to power it, either work or doesn't work.

    You card is the factory OC model. And that's a 2x 8pin card (not 6+8 as you mentioned in post #1). Are you sure that's the correct one?
     
  5. spiteyourface thread starter macrumors newbie

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    Jun 23, 2018
    #5
    Actually no, the image I linked is wrong, mine is the sc2 model with two fans. Anyway it's definitely 6pin and 8pin.

    The powerlink page on the EVGA site describes the product as 'compatible' with all connections, but doesn't really state what it comes with, and only depicts the inner ports that link to the card as being variable, while the external ones are shown as 2x8. Do you know that I can really connect to my Mac Pro out the box? Or will I just wind up with 6+8 to 2x8 converter and be back to square one?
     
  6. h9826790 macrumors G5

    h9826790

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    #6
    Yes, all connectors can be change. You can make the powerlink become 2x 6pin input, and 6+8pin output.
     
  7. AidenShaw, Jul 1, 2018
    Last edited: Jul 1, 2018

    AidenShaw macrumors P6

    AidenShaw

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    #7
    What magic does it have that lets it convert the 75watt+75watt input to the 75watt+150watt output?
     
  8. h9826790 macrumors G5

    h9826790

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    #8
    No, as I said in post #2, that’s way over the official limit.

    It can just practically work. And OP has to accept the risk.
     
  9. spiteyourface thread starter macrumors newbie

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    Jun 23, 2018
    #9
    It sounds to me like the two-Sata solution is the way to go. Does anyone actually running this configuration, or combination of devices, have a testimony or second opinion, before I move forward?
     
  10. Pressure macrumors 68040

    Pressure

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    #10
    The Pixlas mod is fairly simple and easy to implement and is pretty much the recommended way to power something that requires more power than the internal 2 x 6-pin can provide.
     
  11. Squuiid macrumors 65816

    Squuiid

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    Oct 31, 2006
    #11
    Or just return the card and get a GTX 1080FE which is far easier to power and well within specs of the cMP.

    If you have time on your hands you could wait for the 1180FE which will have similar power requirements and is due imminently (August). NVIDIA will very likely support this in macOS but not a given at this stage however.
    https://www.theverge.com/2018/7/2/17524744/nvidia-geforce-gtx-1180-release-date-launch-rumors

    Unless you really have to buy a GTX card right now, days before the launch of the new cards, I would definitely return the 1080Ti and wait. A 1080Ti this late in the game seems like money down the drain to me.
     
  12. spiteyourface thread starter macrumors newbie

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    Jun 23, 2018
    #12
    The Pixlas makes me nervous because this is my primary work machine and I've never dug into a machine like that before.

    I started reading this post on the Pixlas mod, and the first thing it says is I need a an open end dual 8-pin with that link to the Chinese store. I'm not clear whether that should be an open end 8+6 in my case (with the walkthrough assuming dual 8-pin?), or whether I need a dual 8-pin regardless because of power, and then a further Powerlink adapter to make the connection?

    Furthermore, that particular store is currently closed, and in any case I'm wondering why I'm paying $20 for a stripped wire when I could strip a cheaper one myself? But if I did that, what should I be buying to strip?

    What is the risk with the Sata method specifically, what is the 'power spike' danger mentioned in the first reply and is it inherent to this method, or a generic concern? For the record my machine already runs off a Voltage Regulator if that helps any.
    --- Post Merged, Jul 2, 2018 ---
    Thanks Squuiid, that's good information.
    I'm not sure I can return it, especially since the same store has ceased restocking the Founders model, so I would have to get into resale to exchange it.

    Waiting on that new product doesn't sound ideal, even if it's only 'a month'. I'm already trapped in the past waiting for Wacom to get their sh*t together and waiting on another announcement will place me about three dreams deep into Announcement Inception. But if I'm having to resell new purchases anyway, or wait on weird mod orders from China, maybe this isn't getting sorted in a hurry...
     
  13. AlexMaximus macrumors 6502a

    AlexMaximus

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    #13
    This is the best news ever, Thank you so much Mr. Squuiid !!! With a 1180FE and Mojave, a cMP 5.1 will last easily another whopping 3 years and even longer for semi-professionals and YouTubers.
     
  14. clystron macrumors member

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    Aug 11, 2011
    #14
    No magic, the power-supply needs to be able to handle the load. The 75W-limit for the 6pin is in the standard but the connector itself can handle 150W as well. The 8pin does not add any additional power-pins, only a "sense"-pin to detect that 150W can be drawn.
     
  15. h9826790 macrumors G5

    h9826790

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    #15
    Don't expect the 1180 macOS support will be released soon. They usually quite a few months behind Windows.
     
  16. Squuiid macrumors 65816

    Squuiid

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    Oct 31, 2006
    #16
    Perhaps just sell the card ‘as new, barely used’ on eBay and then just buy the 1080 if you can’t wait.
    https://www.nvidia.com/en-us/geforce/products/10series/geforce-gtx-1080/
     
  17. JeffreyA, Jul 30, 2018
    Last edited: Jul 30, 2018

    JeffreyA macrumors member

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    Jul 16, 2018
    #17
    In my testing, the 1080ti will overdraw the dual 6 pins on the board and cause auto shutoff during high load or overclocking. It will draw about 250-275 watts under load according to my testing with msi afterburner. I would use an amp meter to actually get the number right off the cable, but thats too much as its bascially been establied that the 225 watts that the board and boosters are supposed to provide are not enough. I personally use a dual mini 6 pin to 8 pin (y cable) and a dual sata to 6 pin adapter for my MVC flashed 1080ti FE. . I am able to overclock and set the card to run at 300 watts in windows without issue. It costs about 20 bucks for the cables(you can use a dual 6 pin to 8 pin adapter if you don't want to wait for shipping from china). It is "safe" in the sense that it meets all the official electrical standards provided for sata and pcie. MVC did tell me in an email that a single sata to 6 pin adapter works as well but personally I'd be concerned about overdrawing from the sata Port as those are stereotypically not designed for over draw as well as pcie cables and could catch fire in certain high load situations. I'm not saying he is wrong, for normal use it probably is fine. Just know it's not probably not going to overclock as well. The power link option sounds fine as well but you are causing the 6 pins to overdraw regularly and I don't see much overclocking potential if that's ever on the table for you.
     
  18. UCDHIUS macrumors member

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    Honolulu Hawaii
    #18
    I'm about to try this. i'm going to it this way and see what happens. Dual mini 6 pin to 8 pin and SATA power to 8 pin.

    1080Ti, if it shuts off on the first run ill buy the cable and do the pixlas mod.
     
  19. h9826790 macrumors G5

    h9826790

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    #19
    If you can / willing do the Pixlas mod, may be you can do this now, but not wait for something goes wrong.

    JeffreyA was talking about dual SATA (total 110W available) to a single 6pin (rated 75W), not single SATA (55W available) to a single 8pin (rated 150W).

    I wish that's a typo in your post. But if you really want to connect a 8pin to a SATA port, please don't do that, the risk is way too high.
     
  20. UCDHIUS macrumors member

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    Nov 16, 2017
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    #20

    The tower doesn’t get here for awhile so I will order the cable and locks then.
    --- Post Merged, Jul 31, 2018 ---
    MOD DIY, isn't accepting orders right now ): Is there any where else I can get the cable? i'm trying to get everything prepared so once the tower comes in ill be ready.
     
  21. JeffreyA macrumors member

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    Jul 16, 2018
    #21
    I'd consider the pixlas mod a last resort as the power draw isn't measured by anything if you tap the PSU cables. The PSU fan speed won't increase under load as a result. Also please don't use a single sata to 8 pin adapter as that's not going to work very well. I'd either use a single or dual sata to 6 pin, preferably dual sata to prevent overdraw.
     
  22. UCDHIUS, Jul 31, 2018
    Last edited: Jul 31, 2018

    UCDHIUS macrumors member

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    #22
    After further research, I think I have GPU power covered.

    I found a little device called a HD Plex it’s a DC-ATX power supply that is so small it can mount in the case.

    I’ll have a external AC power brick powering it and the main supply socket running out the back.

    Will post up once I get the system together.

    You shouldn’t even notice anything out of the ordinary other than a extra power wire.
     

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  23. h9826790 macrumors G5

    h9826790

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    #23
    I personally don't like the native PSU fan setting anyway. It's not base on any temperature but purely the PCIe slot power draw (not 100% sure if mini 6pin's power draw are also included. I haven't spend time to find out it's actual behaviour).

    e.g. I live in hot Asia. In summer time, if air con OFF, but low GPU usage, even the PSU is at 50C or higher, the fan is still at idle.

    On the other hard, in cold winter, if gaming, even the PSU is 35C, the PSU fan can spin up a lot.

    There were some discussions about how (and why) to keep the PSU temperature low.

    https://forums.macrumors.com/thread...when-using-pc-non-efi-graphics-cards.1946672/

    IMO, it's super strange to let the PSU fan speed base on the PCIe card's power draw but not the PSU's whole power draw, or PSU temperature.
     
  24. JeffreyA macrumors member

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    Jul 16, 2018
    #24
    You can take a generic pcie power cable and cut on end off and make your leads like that. The extra power supply is really not necessary as you have 980 watts available from the stock PSU which should be more than enough for the 1080ti if you plug it in correctly. Your call tho, I heard it helps with longevity but I doubt drawing an extra 75 watts off over using two 6 pin boosters vs using sata power plus boosters is going to do much damage.
    --- Post Merged, Jul 31, 2018 ---
    I get what you mean, but you have to consider that as the device draws more current the more likely the temperature is to increase which is probably why apples engineers implemented it like that. I do agree that it's lazy but I'd rather have the fans spin up under load rather than not at all. Your hot video card is likely louder the the PSU fans anyway.
     

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23 July 1, 2018