3x RX580 on a 750w PSU?

migdilumigdilu Member Posts: 10
Hi, i was building a mining rig, i'm starting with 2x RX580 but i'll add one more in the future. Price is important, i don't want to spend more unnecessarily, but also i don't want to buy a cheap psu that most likely will fail. I was looking at these PSU's, what do you think?.

1 dollar is 19,15AR$

XFX XTR 750W ------------------------------2555 AR$
Thermaltake Toughpower Rgb 750w ----- 2900 AR$
Thermaltake Smart 750w ----------------- 1799 AR$
Corsair CX750M ---------------------------- 2399 AR$
Corsair CX850M ---------------------------- 3050 AR$
XFX PRO 850W ---------------------------- 2769 AR$
Thermaltake Smart M850w --------------- 2500 AR$

Thanks in advance, cheers!

Comments

  • cidmocidmo Member Posts: 446 ✭✭✭
    https://linustechtips.com/main/topic/631048-psu-tier-list-updated/

    grab the cheapest tier 1 PSU u can find
    i run my cards around 100 watts so its no problem for me to fit 5 or even 6 on a 750watt
    but u want to be at 50% load for efficiency
    so try one and find out how much power ur using then add till ur close to 50% load
  • migdilumigdilu Member Posts: 10
    cidmo said:

    https://linustechtips.com/main/topic/631048-psu-tier-list-updated/

    grab the cheapest tier 1 PSU u can find
    i run my cards around 100 watts so its no problem for me to fit 5 or even 6 on a 750watt
    but u want to be at 50% load for efficiency
    so try one and find out how much power ur using then add till ur close to 50% load

    Thanks for the help man!, i can't afford a tier 1 psu, just tier 2, it won't be enought a 750w tier 2 PSU?.
    I didn't understand the load thing, i already mine with mi RX480 at 100% load and is around 105w (overclocked), did you mean PSU load?
  • DavidC1DavidC1 Member Posts: 40
    edited January 2018
    What do you mean you can't afford a Tier 1 PSU? How much does a G2 EVGA 750W cost for example?

    Power Supply would be one thing you don't want to cheap out on. The other power supplies are fine, if you use it as a typical gaming or desktop usage. But you are going to run these power supplies on a significant load 24/7. Is the threat of a fire hazard and/or your power supply dying worth saving $30?

    And try to get a Gold rated power supply. Ignore Bronze.
  • migdilumigdilu Member Posts: 10
    DavidC1 said:

    What do you mean you can't afford a Tier 1 PSU? How much does a G2 EVGA 750W cost for example?

    Power Supply would be one thing you don't want to cheap out on. The other power supplies are fine, if you use it as a typical gaming or desktop usage. But you are going to run these power supplies on a significant load 24/7. Is the threat of a fire hazard and/or your power supply dying worth saving $30?

    And try to get a Gold rated power supply. Ignore Bronze.

    Thanks for the answer!

    Well, in my country we only have EVGA supernova G2 850w and greater, no 750w.

    Tier 1 options in my country:

    - EVGA supernova G2 850w -- 4199 AR$
    - Fuente Sentey 750w Erp750-ps 04 (is this tier one?) -- 2702 AR$

    If the XFX XTR 750w is enough and safe i would prefer that one instead of the EVGA, is too much psu for the 3x RX580, and i'm still working for buying the other 2 580, so keeping so money would be nice too.


  • cidmocidmo Member Posts: 446 ✭✭✭
    sorry i wasnt exactly clear
    u want 50% load on the PSU
    so if u have a 750watt PSU u want to run it at 375watts or close to that
    that would be approx 3x gpu and mobo/cpu
    u can get away with a tier 2 but it has to be a quality brand
    and like dude said nothing lower than gold
    check johnny guru's reviews on them
    the one tier 2 evga i have did melt a 4 pin molex cable at the PSU side
    but that could also have been from crappy riser designs way before ver 006
  • migdilumigdilu Member Posts: 10
    Thanks to everyone, i finally got a EVGA supernova G2 850w, it costs me a lot but i guess i did a good choice.
  • sutheksuthek Member Posts: 324 ✭✭
    migdilu said:

    Thanks to everyone, i finally got a EVGA supernova G2 850w, it costs me a lot but i guess i did a good choice.

    the difference in efficiency between running your power supplies at 50% vs 100% is like 3% efficiency.

    My mining rig is a 13 card rig... and it's powered by 3x 750w evga GQ power supplies.
    works great.

    The split is.
    motherboard + 4 cards on one 750w power supply.
    next 4 cards on another power supply. (750w)
    and last 5 cards on the last power supply (750w)

    doing roughly 650-700w draw from each.

    So to answer your question,
    3 cards and motherboard should be fine on one power supply...

    BUT that's only assuming your motherboard and processor are efficient.
    and you set your power settings on the cards correctly.

    I run a G3930 intel celeron processor which has a very low idle watt draw.
    my i7 desktop draws 100w more at idle.
  • migdilumigdilu Member Posts: 10
    suthek said:

    migdilu said:

    Thanks to everyone, i finally got a EVGA supernova G2 850w, it costs me a lot but i guess i did a good choice.

    the difference in efficiency between running your power supplies at 50% vs 100% is like 3% efficiency.

    My mining rig is a 13 card rig... and it's powered by 3x 750w evga GQ power supplies.
    works great.

    The split is.
    motherboard + 4 cards on one 750w power supply.
    next 4 cards on another power supply. (750w)
    and last 5 cards on the last power supply (750w)

    doing roughly 650-700w draw from each.

    So to answer your question,
    3 cards and motherboard should be fine on one power supply...

    BUT that's only assuming your motherboard and processor are efficient.
    and you set your power settings on the cards correctly.

    I run a G3930 intel celeron processor which has a very low idle watt draw.
    my i7 desktop draws 100w more at idle.
    Thanks for the answer!.

    I have a pentium G4400 so it's almost the same. Now i'm running 2x 480 8GB, each one is consuming 100W, so i think i could add 2 cards more easily, i'm splitting the costs with a friend and sharing the PSU, if in the future i want another card i would buy a cheaper PSU for 2 cards and split it too.
  • sutheksuthek Member Posts: 324 ✭✭
    migdilu said:


    Thanks for the answer!.

    I have a pentium G4400 so it's almost the same. Now i'm running 2x 480 8GB, each one is consuming 100W, so i think i could add 2 cards more easily, i'm splitting the costs with a friend and sharing the PSU, if in the future i want another card i would buy a cheaper PSU for 2 cards and split it too.

    I assume you're getting that watt number out of MSI afterburner?
    It's not accurate... but it's at least a decent "idea".. but will be low and not true.

    I suggest you order a Kill-a-watt (or equivalent) off amazon for like $20. they are dirt cheap.
    this is the one i have (amazon canada)
    https://www.amazon.ca/MegaPower-Monitor-Energy-Voltage-Electricity/dp/B0108YW8W0/ref=sr_1_2?ie=UTF8&qid=1516850220&sr=8-2&keywords=kill-a-watt


    It shows an at-the-wall watt draw..
    What you can do is run the rig with 2 cards... and then get a baseline of watt draw.
    and then add the 3rd card... see the jump.

    Then you'll see a TRUE per card watt usage.

    I found these were really useful when testing the limits of my power supplies.

    Alternatively, a WEMO Insight is handy as it will show you the watt draw... AND give you remote access to the outlet.

    I have had times where my mining stopped... I have no clue why but I'm out shopping...
    I get an email alert from nanopool...
    so I open the wemo app and just toggle the power... 2-3 minutes later my rig is hashing away again.
    (would require you having your computer bios to turn on when power cycled. should be an option in there.)
    (and would require you to get the miner to run on windows starting... or change to linux...)
  • migdilumigdilu Member Posts: 10
    suthek said:

    migdilu said:


    Thanks for the answer!.

    I have a pentium G4400 so it's almost the same. Now i'm running 2x 480 8GB, each one is consuming 100W, so i think i could add 2 cards more easily, i'm splitting the costs with a friend and sharing the PSU, if in the future i want another card i would buy a cheaper PSU for 2 cards and split it too.

    I assume you're getting that watt number out of MSI afterburner?
    It's not accurate... but it's at least a decent "idea".. but will be low and not true.

    I suggest you order a Kill-a-watt (or equivalent) off amazon for like $20. they are dirt cheap.
    this is the one i have (amazon canada)
    https://www.amazon.ca/MegaPower-Monitor-Energy-Voltage-Electricity/dp/B0108YW8W0/ref=sr_1_2?ie=UTF8&qid=1516850220&sr=8-2&keywords=kill-a-watt


    It shows an at-the-wall watt draw..
    What you can do is run the rig with 2 cards... and then get a baseline of watt draw.
    and then add the 3rd card... see the jump.

    Then you'll see a TRUE per card watt usage.

    I found these were really useful when testing the limits of my power supplies.

    Alternatively, a WEMO Insight is handy as it will show you the watt draw... AND give you remote access to the outlet.

    I have had times where my mining stopped... I have no clue why but I'm out shopping...
    I get an email alert from nanopool...
    so I open the wemo app and just toggle the power... 2-3 minutes later my rig is hashing away again.
    (would require you having your computer bios to turn on when power cycled. should be an option in there.)
    (and would require you to get the miner to run on windows starting... or change to linux...)
    I didn't know about WEMO, i will read more about it. Thanks a lot for all your answers and advices!
  • sutheksuthek Member Posts: 324 ✭✭
    migdilu said:


    I didn't know about WEMO, i will read more about it. Thanks a lot for all your answers and advices!

    If you can find them on sale it's good.
    Basically it does two jobs.

    #1 remote control of the power.
    #2 see watt draw.

    Has to be "Wemo Insight" not their other products.

    In theory, you could instead buy two devices to do those tasks though.
    a kill-a-watt for watt draw... and maybe some cheap remote control smart outlet.

    Might be about the same price at the end of the day.

  • migdilumigdilu Member Posts: 10
    That sums it up, i'll think about it and maybe i'll buy one. Thanks!
  • cidmocidmo Member Posts: 446 ✭✭✭
    edited January 2018
    consumer PSU are not rated to run near 100% load for a long time
    this and heat as well as what type of fan is why u run PSU at 50% or near it
    anyone running PSU at 50% for wattage efficiency are not using consumer PSU and/or are running 240
    if u want a power supply thats rated for near 100% load u need server PSU/UPS or some titanium PSU
    johnny guru got info on this too
  • Ericjh801Ericjh801 Utah, USAMember Posts: 371 ✭✭
    Just a comment. I'm running 8 RX580's on 2 750w power supplies without a problem. I am using 240v though, not that it makes too much of a difference I don't think. I'm using around 1200 watts out of the 1500 available. Heat doesn't seem to be a big deal and fans don't seem to be at full power, guess time will tell. That's why they come with warranties too. Swap to another new one and send them back if they fail within 3-5 years.
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