Riser setup (Safety questions)

RazerBoyRazerBoy Member Posts: 9
edited March 2018 in Mining
Hello fellow miners. I come to you in need of aid. I have some questions if my riser set up is correct and if it can handle the load safely. So let's get to it.

This is what I want to do (I believe this to be safe):


So here are my questions:

1. Is it safe for me to split 1x8pin pcie into 2x8pin pcie. And power 2xRX580 with it.
Answer: No and yes. The manufacturer limit is 150W so the cable shouldn't be able to take it. But in reality they can be used to power 2xRX580 and other GPUs that consume about the same amount of power (about 170W or less. theoretical max is for PCIe is 288W), but on higher end GPUs like 1080ti, titan x, vega 56/64 this is not possible (or at least not recommended), due to the GPUs needing more power.

2. Am I safe splitting 1 molex into 2. And then powering 2 risers with them? Just like in the picture above.

3. On the picture you can see I have a chain of 3 molex connectors on the same cable(not my actual cable, the one I'll use will be a high quality PSU molex cable). How many GPU risers can I safely connect to it? Could I do 3x Y molex splitter (male to female) and power 6 GPU risers with it?

4. How much is the max and avg load on a riser? How much can a riser handle?
Answer: Up to 75W (not sure if it could do more?). So if we take my GPU that uses 170W. The riser should be at 75W and the remaining 95W are from the 8pin PCIe connector. This is how I think it works?

5. How much is the max and avg load on a molex cable? How much can a molex handle? (I've seen people say somewhere 135W, but I'm not 100% on this)
Answer: Molex is rated for 132 watts/11 amps. BUT, I still don't know how much it COULD TAKE "safely" (not burn to pieces like the sata/molex connectors do).

My PSU is 3x EVGA SuperNOVA 1200 P2, 80+ PLATINUM 1200W.
I also have 4x LC-Power LC6650GP4 V2.4 (650W) and 1x LC-Power LC1000 (1000W) to help me power all of my GPUs.
I'm using 2x Asus B250 mining expert motherboard.
I need to power 7x Nvidia 1070 GPUs and 14x RX 580 GPUs.

I'm asking how you would power my GPUs. If you had the above PSUs with the GPUs and motherboard I mention.

If you have further question and/or are confused about any part of my explanation please do ask :smile:!
Post edited by RazerBoy on

Answers

  • theclamtheclam Member Posts: 91
    edited March 2018
    Nice job on your picture!
    I think you are safe with RX580's, NEVER more than 2 though. Even better if you under volt them. I prefer SATA and PCIE ver 8 or 7s using splitters with SATA vs molex.
    Also, only split if you must, if you have the connectors, run 1:1 whenever possible.
  • dewminerdewminer Member Posts: 20
    please check the following guide
    https://www.reddit.com/r/EtherMining/wiki/hardware/risers

    to answer your questions:
    1. not a good idea at all, especially with the 6pin to dual 8pin splitter cable
    2. on riser i've measured a 4A power draw on 12V pin with RX570-4G. RX580-8G should take even more
    3. max 2-3 risers on one cable, don't use any splitter
    4., 5. check the mentioned guide

  • RazerBoyRazerBoy Member Posts: 9
    I would also like to add that the main reason for me asking the above question is this.




    I'm one of them stupid people who used sata to molex cables. It didn't work out as you can see. But they did work for 3 months before this started happening. I've already burned 2 cables so far. 1 is currently as we ae speaking alarmingly close to burning (but I don't have the required hardware yet to fix my problem. and shutting off my rigs is just no option at all.... lol :D). It's super hot.

    I've also found this thread https://forum.ethereum.org/discussion/9271/sata-to-molex-adapters. Here the guy explains the difference between GOOD sata to molex cables and BAD ones. I've got the bad ones. He explains that the bad ones tend to always burn up, due to the electrical current melting the plastic around the sata connectors and then the cables inside start moving and then they start touching. Making a short circuit, which then burns both the PSU side sata and the splitter side sata. I've thought about just buying the good sata to molex cables. BUT I do not want to risk anything anymore. I'm done with sata to molex connectors, because they are bad/shit/worthless garbage and I don't recommend them to anyone for anything. Also the problem is that the guy in the video had problems with the bad cables while he was powering SSDs/HDDs.... Which need about 10W of power to run (if not even less). Which really opens your eyes... Since I'm powering 2xGPU riser with them. Not just a petty little SSD.

    So please help me make my miners fire proof :P. The most important questions to be answered for me is 4 and 5. Because I'm really afraid of splitting my PSU molex cable with 3 molex connectors into 6 molexes with Y molex splitters. I really want to know how much power the cable can withstand and how much power a riser uses. For intance. If the molex cable can withstand 200W and the risers use up 30W per riser, then I could split a PSU molex cable with 3 connectors into 6 and I'd be fine. But I also understand that official limits aren't correct. For instance, a 6pin PCIe can take 150W according to the official limit. But I know for a fact it can do MUCH more than that.
  • RazerBoyRazerBoy Member Posts: 9
    edited March 2018
    dewminer said:

    please check the following guide
    https://www.reddit.com/r/EtherMining/wiki/hardware/risers

    to answer your questions:
    1. not a good idea at all, especially with the 6pin to dual 8pin splitter cable
    2. on riser i've measured a 4A power draw on 12V pin with RX570-4G. RX580-8G should take even more
    3. max 2-3 risers on one cable, don't use any splitter
    4., 5. check the mentioned guide

    Could you maybe explain why splitting my 8 pin PCIe to a 2x 8pin PCIe is bad (I know that the official power limit on 8pin PCIe is 150W, but I know it can do A LOT more than that. My current PCIe 8 pin PCIe cables run 2xRX580-4G. And both the GPUs run at 170W. But I don't know how much of that electricity goes through the riser itself.). I know that there are issues with splitting a 8pin PCIe to 2x 6pin is considered bad. But I always thought that splitting an 8 pin to 2x 8 pin is ok. Since I'm currently using 1 PCIe cable to power 2 rx580-4G (they're working at [email protected]). I don't use a splitter on the cable itself. The cable has 2 PCIe connectors on it. But now I'm getting cables that only have 1 connector on each end. But I would really need 2, so I can connect all my GPUs. The problem is related to me being short on money and not being able to buy more equipment in order for me to power all the GPUs with a 1:1 ratio of PCIe cables.
    Post edited by RazerBoy on
  • dewminerdewminer Member Posts: 20
    regarding to point 1, the 8pin is rated to 150W and i'm pretty sure that two RX580 will draw more power from that 8pin (i mean, both together)
    https://en.wikipedia.org/wiki/PCI_Express#Power

    i measured roughly 4amps on riser and 6amps on 8pin mining ether at 1100MHz core clock on RX570-4G.

    the connector itself and the cables provided by the PSU manufacters are most probably capable to deliver much more power then the rated 150Watts on 8pin (12.5 amperes).
    but, if You decide to overload those connectors, i mean to go outside of the specs, You are not on a safe-side anymore.

    if you need to split a cable coming from a PSU and it has only a single 8pin, at least check the cable wires and compare them to a double 8pin cable provided with the same power supply. if the wires diameter match, i would say it should be ok.



  • RazerBoyRazerBoy Member Posts: 9
    dewminer said:

    regarding to point 1, the 8pin is rated to 150W and i'm pretty sure that two RX580 will draw more power from that 8pin (i mean, both together)
    https://en.wikipedia.org/wiki/PCI_Express#Power

    i measured roughly 4amps on riser and 6amps on 8pin mining ether at 1100MHz core clock on RX570-4G.

    the connector itself and the cables provided by the PSU manufacters are most probably capable to deliver much more power then the rated 150Watts on 8pin (12.5 amperes).
    but, if You decide to overload those connectors, i mean to go outside of the specs, You are not on a safe-side anymore.

    if you need to split a cable coming from a PSU and it has only a single 8pin, at least check the cable wires and compare them to a double 8pin cable provided with the same power supply. if the wires diameter match, i would say it should be ok.



    Ah yes, thank you for elaborating. Yes I know that manufacturers tell you the theoretical maximum for PCIe is 150W. But the real maximum is apparently far far greater (but I can't find how much that is. A lot of people are asking the same question, but they only get the answer 150W. Which I'm 100% sure isn't the maximum it can handle safely). But I assume it's between 300-400W. But I will mark question 1 as answered, since I'm fairly certain now splitting it into two and powering 2 gpus is ok to do. Thank you :)
  • dewminerdewminer Member Posts: 20
    actually, i'm doing this splitting as well, but not on PCIe 8pins, but on CPU 8 pin cable. a PSU rated over 800W usually has two CPU cables, each has 4/4 ground/12V wire. i'm connecting one cable to MB CPU connector (obviously) and using the second CPU cable with a CPU to dual PCIe 8pin splitter on a second cable to feed two RX570/580.
  • XcoderXcoder Member Posts: 35
    edited March 2018
    Molex Mini-Fit Jr is max 8 A per pin for the PCIe grade crimp contacts. On a 8-pin PCIe Cable we have 3x 12V. Therefore theoretical max 288 W can be drawn from one cable. But if one of the lines has just slightly worse contact, the other 2 lines will already be overloaded. Thats why the 150 W is a safe limit, with god margins.

    Going beyond 150 W could work over long time, but contacts could degrade, faster if you have high humidity and/or coastal climate.

    And please be aware that Molex Mini-Fit Jr contacts are only usable for 30 mating cycles...
    Post edited by Xcoder on
  • RazerBoyRazerBoy Member Posts: 9
    Thank you for your answers so far guys. I've updated my first post with the answers. I'm still not sure on the first and second question. If someone knows how much the theoretical maximum (not the manufacturer max of 132W) for a molex cable is that would answer both my questions. And I still have sub questions on some of the main questions.
  • XcoderXcoder Member Posts: 35
    You maybe should read my post again... The limit ist 150W.
  • RazerBoyRazerBoy Member Posts: 9
    edited March 2018
    Xcoder said:

    You maybe should read my post again... The limit ist 150W.

    You mean the molex (6pin -> molex)? The theoretical maximum is 150W per cable/connector? I'm confused :P

    Also found this: http://www.playtool.com/pages/psuconnectors/connectors.html
    Post edited by RazerBoy on
  • asusrigasusrig Member Posts: 141
    Nice diagram. What software did you use to create those arrows with curved lines?
  • asusrigasusrig Member Posts: 141
    RazerBoy said:

    I would also like to add that the main reason for me asking the above question is this.




    I'm one of them stupid people who used sata to molex cables. It didn't work out as you can see. But they did work for 3 months before this started happening. I've already burned 2 cables so far. 1 is currently as we ae speaking alarmingly close to burning (but I don't have the required hardware yet to fix my problem. and shutting off my rigs is just no option at all.... lol :D). It's super hot.

    I've also found this thread https://forum.ethereum.org/discussion/9271/sata-to-molex-adapters. Here the guy explains the difference between GOOD sata to molex cables and BAD ones. I've got the bad ones. He explains that the bad ones tend to always burn up, due to the electrical current melting the plastic around the sata connectors and then the cables inside start moving and then they start touching. Making a short circuit, which then burns both the PSU side sata and the splitter side sata. I've thought about just buying the good sata to molex cables. BUT I do not want to risk anything anymore. I'm done with sata to molex connectors, because they are bad/shit/worthless garbage and I don't recommend them to anyone for anything. Also the problem is that the guy in the video had problems with the bad cables while he was powering SSDs/HDDs.... Which need about 10W of power to run (if not even less). Which really opens your eyes... Since I'm powering 2xGPU riser with them. Not just a petty little SSD.

    So please help me make my miners fire proof :P. The most important questions to be answered for me is 4 and 5. Because I'm really afraid of splitting my PSU molex cable with 3 molex connectors into 6 molexes with Y molex splitters. I really want to know how much power the cable can withstand and how much power a riser uses. For intance. If the molex cable can withstand 200W and the risers use up 30W per riser, then I could split a PSU molex cable with 3 connectors into 6 and I'd be fine. But I also understand that official limits aren't correct. For instance, a 6pin PCIe can take 150W according to the official limit. But I know for a fact it can do MUCH more than that.

    I am powering my risers currently with SATA cables included with EVGA power supplies. They look like this:



    But I am also using short extensions cables supplied by the Riser Card manufacturers. Sometimes these are just SATA extension cables and other times they convert SATA to Molex. I'll be keeping an eye on them, so far it has worked out but I've only been running it for 3-4 months.
  • XcoderXcoder Member Posts: 35
    RazerBoy said:

    Xcoder said:

    You maybe should read my post again... The limit ist 150W.

    You mean the molex (6pin -> molex)? The theoretical maximum is 150W per cable/connector? I'm confused :P

    Also found this: http://www.playtool.com/pages/psuconnectors/connectors.html
    8pin PCIe power cables are rated for 150 W
    6pin PCIe power cables are rated for 75 W

    8pin have 3 lines with 12V, 6pin have 2 lines only. The design includes some failure tolerance. If on single line fails, all power goes via the remaining line/lines. This means in worst case 75W over a single remaining line on a 6 pin connector or 2x75W over the 2 remaining lines on a 8 pin connector. 75W on one lines is equivalent to 6.25A which is well bellow the 8 A limit for the Molex connector pins.

    Following the 150/75W rule is therefore very safe. Even with one failed power line the current rating on the remaining lines is not exceeded.
  • RazerBoyRazerBoy Member Posts: 9
    Hello guys,

    I think I've now understand how much the power limits are

    Manufacturer limit
    Theoretical max limit
    Molex no official limit (about 135W is considered safe)
    306W
    6 pin PCIe
    75W 192W (or 288W)
    8 pin PCIe
    150W 288W
    I've got the number from here: http://www.playtool.com/pages/psuconnectors/connectors.html#peripheral

    Molex: Has 1 yellow wire that is 12V and 1 red wire that is 5V. The maximum current per wire is 13amps. So 12V + 5V = 17 V. 17V * 13A = 306W

    6pin PCIe: Has 2-3 yellow wires which have 12V per wire. The max current per wire is 8amps. So 2 (or 3) * 12V = 24V (or 36V). 24V (or 36V) * 8A = 192W (or 288W).

    8pin PCIe: Has 3 yellow wires which have 12V per wire. The max current per wire is unknown (let's say it's 8amps, just because the 6pin PCIe has 8A). 3 * 12V = 36V. 36V * 8A = 288W.

    I now believe this is the correct numbers. If anyone disagrees please let me know. Also tell me why you disagree (provide a link to a website which has the correct ampers/volts on cables) and what the real number should be.



    Now to answer my questions from my first post:

    1. Is it safe for me to split 1x8pin pcie into 2x8pin pcie. And power 2xRX580 with it.
    Answer: No and yes. The manufacturer limit is 150W so the cable shouldn't be able to take it. But in reality they can be used to power 2xRX580 and other GPUs that consume about the same amount of power (about 170W or less. theoretical max is for PCIe is 288W), but on higher end GPUs like 1080ti, titan x, vega 56/64 this is not possible (or at least not recommended), due to the GPUs needing more power.

    2. Am I safe splitting 1 molex into 2. And then powering 2 risers with them? Just like in the picture above.
    Answer: Yes, splitting it into 2 is OK. If you have this scenario. 8pin PCIe to molex is should be ok. You can then split the molex end of the cable into 2 more. So in this case it would go 8pin PCIe (male) to molex (male) to molex (female) to 2xmolex (male). This is acceptable. But I would not recommend splitting it into 3 molexes and powering 3 risers. Since 3 riser = 3 * 75W = 225W. And the limit on the PCIe 8pin is 288W, which is rather close.

    3. On the picture you can see I have a chain of 3 molex connectors on the same cable(not my actual cable, the one I'll use will be a high quality PSU molex cable). How many GPU risers can I safely connect to it? Could I do 3x Y molex splitter (male to female) and power 6 GPU risers with it?
    Answer: I can safely connect 2 risers. I can't split it with 3x Y molex splitters and power 6 GPU risers with it.

    4. How much is the max and avg load on a riser? How much can a riser handle?
    Answer: Up to 75W (not sure if it could do more?).

    5. How much is the max and avg load on a molex cable? How much can a molex handle?
    Answer: Molex is rated for about 135W. The theoretical max is 306W.

    If you think something is wrong/disagree with the above, please let me know and provide an explanation/evidence to support your claim.
    asusrig said:

    Nice diagram. What software did you use to create those arrows with curved lines?

    It's called good old Paint xD! This are the curved lines :P.

    Open questions:
    6. So if we take my GPU that uses 170W. The riser should be at 75W and the remaining 95W are from the 8pin PCIe connector. This is how I think it works? Does the riser ALWAYS draw as much as it can? Is it always at 75W?

    7.


    This is my PSU EVGA SuperNOVA 1200 P2, 80+ PLATINUM 1200W. You can see on the image above that it has 4 SATA, 2 PERIF and 2 CPU exits. Now my question is this. Are the SATA and PERIF exits the same? Could I connect 6pin PCIE (male) to molex cables to the SATA ports? Do the SATA ports supply the same amount of energy as the PERIF ports do? What about the CPU port? Can I connect a 8pin PCIe to molex cable to the CPU port and be fine (I've seen someone in this thread saying he's doing this, but is this really ok to do. Just want more people to confirm this). I just want to know if I can use ports that are labeled by the manufacturer as SATA as PERIF ports and vice-versa. Also if you can use a CPU slot as another Molex slot.

    If we answer the above 2 question I'll post a few diagrams of riser setups which I think are good/safe. I'll also post which riser setups are bad/unsafe. I'll also try to order them in a tier list (from best to worst) and I'll give a explanation with the pictures so people get why I think they're the best/worst. Then you can tell me what you think, if my assumptions are correct.
  • RazerBoyRazerBoy Member Posts: 9
    edited March 2018
    Hey guys. I already posted a comment. But it was put up for review :P and because it was a really long comments I CBA to rewrite it again. So check back tomorrow or later this evening after a nice mod reviews my comment ^^.
    Post edited by RazerBoy on
  • iamnoobplzhelpiamnoobplzhelp Member Posts: 239 ✭✭
    I've said this before, and I'll say it again

    The safest way to power cards using risers #1, using a server power supply and #2 using 6 pin powered riser cards.

    I use a server power supply like this to power the cards and the risers for up to 8 cards.
    http://www.parallelminer.com/product/hp-1200-watt-power-supply-kit-for-gpu-mining-platinum-94-zec-dash-eth/
    Then I use a ~400w PSU for the motherboard and SSD.

    You also want to use PCIe 6 pin powered risers, like this:
    http://www.parallelminer.com/product/ithoo-usb3-0-pci-express-1x-to-16x-extender-riser-card-adapter-w-24-cable/

    Then use a GPU power splitter like this to power both the card and the riser:
    http://www.parallelminer.com/product/18awg-pci-e-6pin-to-dual-8-pin-y-splitter-extension-cable-2x-62pin-cable-6in-each-side/
  • RazerBoyRazerBoy Member Posts: 9
    My comment was reviewed by a moderator now and was posted (sorry for my spelling mistakes and bad english. I couldn't edit the post) :)! It's the one above this one:
    RazerBoy said:

    Hey guys. I already posted a comment. But it was put up for review :P and because it was a really long comments I CBA to rewrite it again. So check back tomorrow or later this evening after a nice mod reviews my comment ^^.

    I've answered all the initial questions (BUT still not 100% if they're all correct. If you think/know they're not, tell me and explain to me why you think it's wrong (and possibly provide links ^^)!. But I still have 2 questions left to answer :)! After that everyone gets "nice" diagrams of riser setups and cake !

    I've said this before, and I'll say it again

    The safest way to power cards using risers #1, using a server power supply and #2 using 6 pin powered riser cards.

    I use a server power supply like this to power the cards and the risers for up to 8 cards.
    http://www.parallelminer.com/product/hp-1200-watt-power-supply-kit-for-gpu-mining-platinum-94-zec-dash-eth/
    Then I use a ~400w PSU for the motherboard and SSD.

    You also want to use PCIe 6 pin powered risers, like this:
    http://www.parallelminer.com/product/ithoo-usb3-0-pci-express-1x-to-16x-extender-riser-card-adapter-w-24-cable/

    Then use a GPU power splitter like this to power both the card and the riser:
    http://www.parallelminer.com/product/18awg-pci-e-6pin-to-dual-8-pin-y-splitter-extension-cable-2x-62pin-cable-6in-each-side/

    Ah yes. Thank you for confirming that ^^! I was thinking about the same thing literally a few hours before you made your post. Tell me something, are the parallel miner PSU kits reliable? Are they durable? Do they run for years? I am a bit skeptical about them, just because they only have a 30 day warranty. Also, where do they ship from and is the shipping free if I order a lot? I'm interested in this because I'm from europe and the taxes can be really high for importing stuff from some places.
  • peshetomanpeshetoman Member Posts: 78
    server PSU are reliable most of the time due to way they are build, but are noisy as hell...
  • iamnoobplzhelpiamnoobplzhelp Member Posts: 239 ✭✭
    edited March 2018
    @RazerBoy
    Server PSUs are meant to be running 24/7. ATX PSUs are meant to be running at 80% load for 8 hours per day. So server PSUs will always outperform and outlive ATX PSUs in a mining situation.

    That being said, I bought some third party server power supplies and tried using parallel miner breakout boards with poor results. The breakout board ended up frying. This was my problem because I didn't use their power supply.

    All of my mining machines now have their power supplies and their breakout boards. They have been running for almost a year now pretty much non-stop. They have been running with zero issues. When I did have issues with the melting breakout boards, they sent me a free breakout board and PSU replacement; even though it wasn't their PSU. I have a lot of respect for them. I think they only offer the 30 days warranty because the PSUs are 2nd hand. That's the only way they can sell them so cheap.

    Maybe there is a supplier in the EU that has something similar. Take a look.
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