Add2PSU - Do I connect ALL GPUs to ONE PSU or do I balance them?

farwarefarware Member Posts: 116
Is anyone using the Add2PSU adapter? I want to combine two PSUs but my question is whether I connect all GPUs to one PSU via PCIE or if I connect two GPUs to PSU-1 and two other GPUs to PSU-2?

What is the safer method? Would be great to hear from someone who has done this before.

Comments

  • MrYukonCMrYukonC Member Posts: 627 ✭✭✭
    No, you evenly split GPUs across both PSUs.

    I am running the same setup on 3 different rigs -- all with 2 PSUs each. The 1st PSU runs the mobo + CPU + 3 GPUs and the 2nd PSU runs 3 GPUs.

    Also, before doing this, I would strongly recommend using USB 3.0 powered risers and NOT the cheap ribbon powered risers. With the USB risers you can power them from either PSU.
  • farwarefarware Member Posts: 116
    Thanks for the detailed answer.

    I wasnt even aware of USB risers, only powered risers. Thanks for the heads up!

    I suppose better safe than sorry. Right now I am running two machines (aside from my main rig with 4 cards) which is a little inefficient so I want to turn the two machines into one big rig but 1350W PSUs are expensive these days.
  • farwarefarware Member Posts: 116
    I only use cards with their own PCIe power connectors, do you think it would still be better to get USB powered risers? Seems a little overkill. The cards will mostly draw power from whatever PSU they are connected to so balancing them is possible
  • MrYukonCMrYukonC Member Posts: 627 ✭✭✭
    First of all, what cards are you running? I run 18x 280X and 3x 270. In close proximity of each other when installed directly on the motherboard, it was too difficult to keep the heat down.

    I now run them all on custom built stands and make use of the USB 3.0 risers and now all of my cards' temps are between 57C - 67C with fanspeeds between 45% - 50%. Being out of the case and off the motherboard has worked wonders for their temps.

    For you, you would simply plug 2 cards into the 1st PSU and 2 cards into the 2nd PSU.

    Here is a post I made last night trying to help another user out:
    https://www.reddit.com/r/ethereum/comments/3of9cr/mining_rig_question/cvxmyl2
  • farwarefarware Member Posts: 116
    MrYukonC said:

    First of all, what cards are you running? I run 18x 280X and 3x 270. In close proximity of each other when installed directly on the motherboard, it was too difficult to keep the heat down.

    I now run them all on custom built stands and make use of the USB 3.0 risers and now all of my cards' temps are between 57C - 67C with fanspeeds between 45% - 50%. Being out of the case and off the motherboard has worked wonders for their temps.

    For you, you would simply plug 2 cards into the 1st PSU and 2 cards into the 2nd PSU.

    Here is a post I made last night trying to help another user out:
    https://www.reddit.com/r/ethereum/comments/3of9cr/mining_rig_question/cvxmyl2

    I mostly use 7950 and 280x but I use custom-built rigs with 5 fans on top so temps will be like 50-60

    I decided against USB risers because I already have the regular risers and many sources confirm they cant overheat because the actual power goes through the PCIe connectors from PSU-1 or PSU-2.

  • MrYukonCMrYukonC Member Posts: 627 ✭✭✭
    Okay. Good luck! Make sure to report back.
  • ScryptZillaScryptZilla Member Posts: 7
    Are you guys able to elaborate on the how your connecting the Risers and GPU power connectors?

    I've currently have the following setup for 4 GPU's

    Main PSU connected to the mobo/ 2 GPU's (6+8 connectors) + 4 x molex powered risers.

    2nd PSU is connected to the other 2 GPU's (6+8 connectors).

    I'm using something similar to this to connect the PSU's together.
    http://www.frozencpu.com/products/5637/cpa-167/Lian_Li_Dual_Power_Supply_Adapter_Cable.html

    The rig powers up well and Win 10 detects all GPU's.

    I run ethminer to check the list of devices and all 4 are listed.

    When I start running ethminer to start mining, it goes through the motion and starts hashing for about 30 secs then the screen freezes.

    I restart the rig and everything is working fine. I moved the GPU power connectors from the 2nd PSU to the main PSU to test the cards.

    I restarted and everything is fine running off the main PSU (1200 watt Silverstone Strider Gold ) but pulling about 1350 watts from the wall.
    I wanted to distribute the load over the 2 PSU but it keeps crashing when I start mining Ether.

    anyone have any ideas if the configuration above is wrong? I've tried most of the suggestions on this forum but I can't seem to get it working for Eth.

    cheers
    SZ

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