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Thread: Is 16 AWG really better than 18 AWG? (SSR-1200PD for Mining)

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    Quote Originally Posted by Tim@PSUTest View Post
    This issue came up where I worked in 2011. This is when I found out about Bitcoin. It had just crashed form $31.00 to about $1.50.

    The pins on the two +12-volt wires on the 24-pin connector were overheating on power supplies used for mining. There is a power supply specification somewhere that calls out the Molex HCS pins rated at 13 amps when used with 16 ga wire. Keep in mind the current rating is dependent on the number of positions in the connector housing and the crimp tool may be different than the one for 18 ga wires.

    I had production where I worked make up a harness using 16 ga wires and the HCS pins for the +12-volt wires on the 24-pin connector. This was plugged into the proper mating Molex connector on a PC board. I then loaded up the two +12 wires 13 amps per pin using an electronic load.

    I then measured the temperature rise after it stabilized. I then did the same test with power supplies form different manufacturers that also used 16 ga wires and “Molex equivalent” pins.

    The temperature rise of the pins on the power supply made by Super Flower was less than the Molex HCS pins. The rise of the pins from the other manufacturers was somewhat higher.

    We informed our other vendors to do the same test and change to “equivalent” pins that were at least as good as the true Molex pins.

    This would be a good test for power supply reviewers to include.
    The problem is, people that buy mining hardware are trying to get away with the cheapest garbage possible.

    Just take a look at "mining PSU" on eBay and see all the garbage that's out there. Then they use SATA splitters that aren't even UL94V rated.... it's a shit storm.

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    Apologies for this being late, I've been unwell.

    Cass-Olé, you are a fountain of knowledge, thank you very much for sharing it so generously.
    Quote Originally Posted by Cass-Olé View Post
    Jon & some of the other forum dwellers here know more about this than I do. If you emailed Sesonic AU, told them your hardware plans & they green-lit the project, save the Rep's email ... ... ...
    I asked if I could purchase 16 AWG cables for over 250W devices and they basically said that 18 AWG will be fine (I have saved the Rep's email ... ...). I've now emailed Seasonic UK to see what they say.

    Quote Originally Posted by Cass-Olé View Post
    ...relative to 9A of course
    Yeah, it seems like 9A is the lower limit within a kind of a safe range of 16 AWG cables in general.

    Quote Originally Posted by Cass-Olé View Post
    In order to easily upgrade a Seasonic 18g GRFX cable, any maker's 18g cable, what I've done here for myself & others is to buy some Corsair Type3 pigtail (dual 8pin 6+2) cables..

    ...When you say you have a Vega, a GTX 590 & a 295x2 on the way, in the end, is your plan to use all 3 at same time? Do u plan to mine with any of them? If not, the Seasonic chart advises to deploy a pair of cables per card & all indicators say to not use one dual-8pin cable on cards like those. You have at least 4 GRFX 8pin headers & possibly 5, so how many cards do u plan to pair to your 1200w?
    That's pretty neat, and before I take up anymore of your time with this part, to be clear I'm still on the fence with being able to DIY these myself, but either way I'm learning a lot which is always good.

    Ensourced have replied and say they use "Molex Minifit Jr connectors that are rated at 13A." so if I don't DIY and if I can't find anything more affordable, I'm thinking of going with them despite not wanting any kind of fancy braided cables - just something reliable with sustained loads.

    I looked up the HCS you guys mentioned and tried to compare them to the Mini-fit Jr connectors, a lot of them are 18AWG but there are 16AWG pins available. Then depending on whether they're wire-to-wire or wire-to-board and what types of metal are on the pins, Current limits vary.

    https://www.molex.com/pdm_docs/ps/PS-45750-001-001.pdf
    And there's 16 AWG Crimp Terminal (Part#: 39000077) that seems to be 12.A wire to board, with a field (?) temperature of 65 degrees C max. (does "field" mean ambient?)
    I'm not sure if field temperature is the specified max under sustained load though as other requirements/specs further down, show the max temps as higher.

    https://www.molex.com/pdm_docs/ps/PS-5556-001-001.pdf
    This seems to be the Mini-Fit Jr. (the first 16 AWG terminal I could find) and it shows wire to wire, 2 & 3 circuit as only getting 9A from 16 AWG, with 80 degree max temp. (Page/Sheet 7)

    - Regarding GPUs, (Vega: 345W, 590: 360W and 295x2: 507W) I want room to expand in future and have the option to mine with at least most of them at the same time (one will probably be used for gaming) - at max wattages that adds up to a total of 1212W - a bit too close to the limit :P so I intend to tweak power usage to generally keep them at around 300W.

    - Essentially, the goal is to be able to run at least 300W sustained load from each PSU 8-Pin header (or 150W from the pigtailed cables) without the risk of burning down my house.
    9A should give me a theoretical 324W, so as long as I stay below that with 13A connectors and 16 AWG cables, assuming ambient temps don't go above (roughly) 45 degrees C, I should be able to sleep safely at night, right?

    As for how many cards - as many as possible, within reason. In the future it would be nice to have the option to go to 150W cards and run 2 of them on each of the 4 or 5 GRFX 8-Pin headers, basically (safely?) doubling the rating of generic/standard 18 AWG cables & connectors found in mid-range PSUs.

    Quote Originally Posted by Cass-Olé View Post
    ***Please seek advice on whether the 18g Seasonics - used in pairs - are adequate for mining, since I personally wouldn't use them on a 295x2***
    Fair enough, I agree 100% and wouldn't expect a pair of the 18 AWG Seasonics to safely support sustained 500W by any stretch of the imagination. Also thank you for the Silverstone quote, definitely good to keep in mind.

    Quote Originally Posted by Cass-Olé View Post
    Woa thanks, that 'Effective Gauge' chart is really cool.

    Quote Originally Posted by Cass-Olé View Post
    Below, the FSP Aurum PT 1200 (these days they come with all-black cables) doubles-up the CPU 8pin wires by using two 18gauge per terminal (16 wires on 8 terminals) = a 15AWG CPU cable
    Attachment 3902
    That is badass.

    Quote Originally Posted by Cass-Olé View Post
    I have an FSP Aurum 1200 here (sold the cables to it) in an X99 build I put together last week, includes 16awg purples from FrozenCPU / 16g blacks from MainFrame Customs on the GRFX/CPU/24pin (the PCI-E_PWR 8pin header gets 18g 'fuscia' for now anyways). I might try the doubled-wires design (18/18) on my next GRFX cable project (=
    Impressive, that must be super reliable. And 18/18 would give you an effective gauge of 15 AWG, nice, would you intend to mine with that, run gaming VMs or just make everyone jealous? :P
    Quote Originally Posted by Cass-Olé View Post
    Attachment 3904
    Hand-made cable set above was last seen on my NZXT Hale90 1200 (also by FSP), now converted over for the Aurum
    Attachment 3905
    Nicely done.

  3. #23
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    Quote Originally Posted by Jon Gerow View Post
    The problem is, people that buy mining hardware are trying to get away with the cheapest garbage possible.

    Just take a look at "mining PSU" on eBay and see all the garbage that's out there. Then they use SATA splitters that aren't even UL94V rated.... it's a shit storm.
    And when they also use those dodgy Molex to SATA adapters - the slim ones have a high chance of coming defective from the factory, causing an arc discharge... then it gets even more insane.

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