What's your opinion: The Eternal Question

Comments

• mikeo Member Posts: 176 ✭✭

  July 2017

  I'm running 6 AMD RX cards with risers off of one EVGA 1000 GS PSU. This psu supports 6 individual PCIe cables in addition to SATA and PERF.
  
  I use this splitter to power the card and riser from one PCIe power cable:
  https://www.amazon.com/Cable-Matters-2-Pack-Splitter-Y-Cable/dp/B01DV1Z57C/ref=sr_1_1?ie=UTF8&qid=1499724617&sr=8-1-spons&keywords=pcie+splitter+8+pin&psc=1
  
  And this riser (note 6-pin PCIe connector):
  https://www.amazon.com/6-Pin-Powered-PCI-E-Express-Riser/dp/B071G2MGCD/ref=sr_1_1?ie=UTF8&qid=1499724779&sr=8-1-spons&keywords=PCIe+riser+6-pin&psc=1
  
  

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• RDPP Member Posts: 71 ✭

  July 2017

  I would say YES (all same as PSU) because 2 PSUs always have different/unequal loads and i can imagine it will fk up your risers/gpus sometime but i don't have any proof for that

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• ecs87 Dekalb, ILMember Posts: 339 ✭✭✭

  July 2017

  I've been running 7 GPUs on a new rig for over 24 hours using 2 PSUs (one is a server PSU). So far, zero issues (other than a STRIX RX480 that I'm going to have to RMA...for the third time).

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• RDPP Member Posts: 71 ✭

  July 2017

  for over 24 hours

  
  this is no valid test-period - let's see in a couple of months, i hope you'll be fine

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• ecs87 Dekalb, ILMember Posts: 339 ✭✭✭

  July 2017

  Hytech2k has been running them for over a year (unless I missed a post about him/her frying them): http://forum.ethereum.org/discussion/comment/24618

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• Saph Member Posts: 72 ✭

  July 2017

  Decent comments but it looks like the eternal question is going unanswered.

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• mikeo Member Posts: 176 ✭✭

  July 2017 edited July 2017

  .

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• myriatech Member Posts: 29 ✭

  July 2017

  it makes zero difference. the only important question you need to ask yourself is whether you are drawing more than the rated psu wattage with everything connected to those rails. power is power and psu's only job is to supply it. rule of thumb is to not run at the rating of the box or you will burn it out over time.

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• Saph Member Posts: 72 ✭

  July 2017

  @myriatech so it doesn't matter if the GPUs come on at different times? Conventional wisdom says that's a question at least worth looking into. A PSUs job is to regular power, not just supply it.
  
  Anyway I'm running 6x1070s off two PSUs with all the risers connected to the same PSU without issue. 8 days no crash.

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• lablett Member Posts: 332 ✭✭

  July 2017

  From a technical perspective both options work and I have both. I have moved to Dual PSU because the cabling is simpler and the risk is lower. Cabling is simpler as I have a 1 to 1 on all cables. The risk is lower because each riser and GPU has its own power cable. Dual PSU does add some new challenges but these are easy to overcome. If you buy quality PSUs then single or dual are both viable. However, I personally feel happier with a 1 to 1 cable approach.

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• myriatech Member Posts: 29 ✭

  July 2017

  The job of a power supply becomes unable to regulate power when you run at max or over, which is why it makes zero difference how you run risers but makes all the difference in total pulled wattage. Regulating power under a psu's load isn't a consideration because it's not like an HVAC system that needs to be spec'd for the amount of load.
  
  Risers draw nearly no power. For safety sake consider each one is 5 watts. Consider a gpu will be 150. If you have 2 750w psu's you can't connect more than 4 gpu's as that yields 600 watts. You could then connect all risers as that would put you at 630, right where you want to be for one 750 psu. The rest of the computer can run off the other one.

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• lablett Member Posts: 332 ✭✭

  July 2017

  Actually, if you are running dual PSU then should power the riser and GPU from the same PSU. This way if a PSU does not start then it will not be powered.

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• Saph Member Posts: 72 ✭

  July 2017

  That was my original thought process @lablett but the internet seems fairly split on the correct method, hence the op.
  
  I struggled to find PSUs at all so I'm running 2x 850w plat numbers pulling around 900 from the rig, wasting capacity I know but I'll swap them out in the future I reckon.
  
  @myriatech so what you're saying is so longer your using an appropriate amount of power per PSU it really doesn't matter at all?

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• myriatech Member Posts: 29 ✭

  July 2017

  Correct, no reason to over complicate it. Just use math.

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• lablett Member Posts: 332 ✭✭

  July 2017

  Having the extra capacity is a good thing so the can get a rig stable and then tune. I also opted for a similar wattage and I also wanted to future proof my rig.

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• Saph Member Posts: 72 ✭

  July 2017

  Productive talk, thanks guys.

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