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Thread: Combining 2 PSU in a mining rig

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    Question Combining 2 PSU in a mining rig

    Hi everyone,
    I am in the process of upgrading my cryptocurrency mining rig. Currently it consists only of one Radeon 280x GPU powered by a 750W PSU but two more GPUs are on their way toghether with a 1000W PSU. In some time I would like to uprade the rig to the final amount of 6 GPUs powered by two 1000W PSUs. I have found 3 options after some time spent looking for:

    1. using this adapter:

    http://litecoinminingparts.com/shop/...adaptor-cable/

    I am not sure about this adapter as it connects the PSUs through the MoBo. The rig runs 24/7 and I really do not want to fry any component.

    2. using this adapter:

    http://www.add2psu.com/

    This one seems to be the same as the third option. However there is no notion about the need to load the 5V rail toghether with the 12V.

    3. DIY following the guide here:

    http://www.jonnyguru.com/modules.php...ory&ndar_id=27

    At the end there is a notion to load the 5V rail alongside with the 12 V rail. It says that a dummy resistor will be enough. Can someone explain how to make the dummy resistor plug?
    I have also found a reccomendation that a good way to load it is to connect a 12V lighting bulb to the 5V wires. Do you think it is good idea?

    The GPUs will be connected with powered raisers. They are powered via the PSU molex connectors. I want to run 6 120mm fans per PSU to improve cooling of the GPUs. Do you think it is ok? I don't want to overpower any rail of the PSUs.

    Finaly I have read that it is wise to power the GPUs by wires from different rails like the 8pin PCI-E from 12V2 and 6pin PCI-E from 12V3. Is there any logic behind this? Wouldn't it do even more harm?

    The PSUs I am considering to use are EVGA Supernova 1000W P2. However I am not sure about the single 12V rail. Each of them will power 3 GPUs. Do you think it is a good option or would you recomend some other PSUs?

    Thanks for any advice or recommendation. This website is amazing. I have never thought how important is to choose a solid PSU.
    Last edited by JimmyJoe; 01-28-2014 at 05:39 PM.

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    Default

    If you go with anything like option 1, make sure the adapter uses 16 gauge wiring between the two ATX connectors... that one looks like it might be a little light there.

    Don't worry about loading the 5V rail with any DC-DC design like the EVGA. They don't care if the minor rails are unloaded.

    Remember that if the six cards you're powering happen to be 290s, you'll likely need to plug into two different circuits. I haven't quite figured out my own strategy there... I plan on eventually building two six card rigs, and I only have so many blank spaces in the breaker panel to make use of. There will only be two 20A circuits available for mine. I may have to stop at five cards if I do 290s, but I'll see how it goes.

    If you don't have the mainboard yet, one that has an additional power connector for the PCI-E slots will negate the need for powered risers. The MSI 990FXA-GD5 is the one I'm looking at.

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    Default

    Thanks for the advice. Actually this is the MoBo I am going to use. But not because of the extra pci-e connector. It is cheapest MoBo with 6 pci-e slots. I wonder how much power can be supplied by the extra pci-e connector. As far as I know the MoBo supplies 75W to a GPU. I assume that this board is designed to deliver not more than 150W as there are only 2 pci-e 16x slots. By using the additional 6 pin connector another 75W could be routed to the GPUs via the MoBo. Together it is still just 225W which enough to power only 3 GPUs. The other two GPUs still need to be powered by the raisers. But how can one know which 3 GPUs are left without the extra juice? And I am not sure about how much power can be supplied to a GPU through a 1x - 16x raiser. However these are only my assumptions and could be miles away from the truth.

    One more question came to my mind. Is there a difference in the current drought by the PSU between the US 110V and the European 230V?

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    Obviously primary side at 110V has to draw about twice as much current for the same power compared to the 230V.

    This will drop efficiency a bit, usually by 2-3%

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    Can't say how much extra that connector could supply, but since it's a 6 pin PCI-E you'd probably want to stay below 150W on it. That's assuming the board traces can handle that. This would be in addition to the power the board would already be able to supply.

    If you're worried about it there's no harm in using powered risers as well. My suggestion there would be to use the USB models - they're a little better built than some of those slapdash Molex enhanced ones I've seen, and the longer USB connections give you a lot more flexibility in where you mount the actual GPUs.

    I might actually do that anyway, just because those things look so professional. But they will cost you a bit...

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    Default did it work?

    So did it actually work? What approach did you use?
    I am interested in doing something similar. I am considering connectpsu adapter that looks a bit safer.

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