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Author Topic: Antminer S7  (Read 1829 times)
QuintLeo
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November 03, 2015, 11:45:23 PM
 #21

That doube-4-pin Molex to PCI-E adapter will almost definitely NOT handle the load a S7 would put on it - and it's doubtfull that your power supply puts enough current out on the "peripheral bus" +12V supply anyway.

 The wiring is WAY too light, will probably melt and short out.



 Garage should be fine, if it doesn't leak and if it's secure enough you don't have to worry about someone stealing your miner(s).
 You're also more likely to have at least one existing 220V outlet there to power an S7 with from a GOOD power supply.
 Many moons ago, I had a setup in a slightly modified storage shed (I added some airflow access, a breaker panel and outlets) running a bunch of computers - ran air in under the eves on the South side and out the East due to prevailing winds, worked fine and stayed dry and close to ambient temps. Solid metal walls, solid door, and a good lock in a backyard with a solid fence around it made the setup hard to notice, and the comps I had in it were older ones that weren't worth a lot anyway.


 Bitmain's site was up a couple minutes ago, they might have been doing a "price adjustment" and had it down for a short while earlier.


 *IF* the current Bitcoin price holds up, an S5 should barely be profitable after the halfing for a while, and an S7 somewhat but not greatly so for months, even with the diff increase rate I forsee between now and then - but neither is going to make a LOT after the halfing even at the current $400ish price, you had best plan to hit RoI on either by end of July IMO even if the Bitcoin price stays high.

 If the current Bitcoin price drops back down into the mid-$200s soon, the situation stays the same except RoI is a ton less likely and the S5 will probably NOT remain profitable at all after the halfing (the S7 will still be, but BARELY).
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November 04, 2015, 01:34:20 AM
 #22

That doube-4-pin Molex to PCI-E adapter will almost definitely NOT handle the load a S7 would put on it - and it's doubtfull that your power supply puts enough current out on the "peripheral bus" +12V supply anyway.

The wiring is WAY too light, will probably melt and short out.

Thank you for agreeing with me on it  I can't believe someone said to use a molex to PCIe on mining equipment.

It is seriously asking for a fire if using cheap adapters like it.   Getting a better PSU is the best way.  To possibly kill a S7 over a hundred bucks or so makes no sense.
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November 04, 2015, 10:48:13 AM
 #23

For some of the older lower-power miners that molex-to-PCI trick would be tolerable. I ran one of my Gridseed blades on 2 molex per side for a while, but that was less than 4 amps or so per side so only 2 per molex, which is well within their rating and the capability of the wiring.
It would be practical to run a 6-pin PCI-E power connector that is running within the PCI-E specs from 2 molex, but most miners are pushing the connectors to closer to the limits of the CONNECTOR, which is way outside what most 4-pin molex peripheral connectors AND THEIR WIREING are designed to handle.
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November 04, 2015, 12:49:39 PM
 #24

If you have thick wire, it is OK to use the molex connector.

https://bitcointalk.org/index.php?topic=62686.msg732348#msg732348

12V only:
"Molex" connector (PS-8981-4M*/4P*) - depending on wire gauge from 6 to 10 Amps per motherboard connector.
Sata connector - 1.5 Amps per contact (3 contacts per connector) = 4.5 Amps per motherboard connector.
PCI-E 6-pin connector - up to 13 Amps per each wire (3 12V wires per connector) = theoretically up to 39 Amps but ATX spec limits PCIe-PEG connectors to 75 W (6.25 Amps).

When in doubt, RTFS(1).

Notes:
(1) S standing for SpecSheet:
http://www.molex.com/catalog/web_catalog/pdfs/I.pdf
http://www.molex.com/molex/products/datasheet.jsp?part=active/0002081201_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US
http://www.molex.com/molex/products/datasheet.jsp?part=active/0675810000_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US
http://rhu004.sma-promail.com/SQLImages/kelmscott/Molex/PDF_Images/987650-3722.pdf
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November 04, 2015, 07:10:29 PM
 #25

yeah i ran a 2 molex to 1 pcie splitter for awhile.. ran both molex lines separate from PSU to power 1 pcie connector on an avalon 4.1 and also BFL monarch before that
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November 04, 2015, 07:49:01 PM
 #26

If you have thick wire, it is OK to use the molex connector.

https://bitcointalk.org/index.php?topic=62686.msg732348#msg732348

12V only:
"Molex" connector (PS-8981-4M*/4P*) - depending on wire gauge from 6 to 10 Amps per motherboard connector.
Sata connector - 1.5 Amps per contact (3 contacts per connector) = 4.5 Amps per motherboard connector.
PCI-E 6-pin connector - up to 13 Amps per each wire (3 12V wires per connector) = theoretically up to 39 Amps but ATX spec limits PCIe-PEG connectors to 75 W (6.25 Amps).

When in doubt, RTFS(1).

Notes:
(1) S standing for SpecSheet:
http://www.molex.com/catalog/web_catalog/pdfs/I.pdf
http://www.molex.com/molex/products/datasheet.jsp?part=active/0002081201_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US
http://www.molex.com/molex/products/datasheet.jsp?part=active/0675810000_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US
http://rhu004.sma-promail.com/SQLImages/kelmscott/Molex/PDF_Images/987650-3722.pdf

The problem is most adapters are not built up to this standard on molex adapters.  If you go to a computer store most are not good enough gauge I think it's safe to say.

There are a few on the forums though who do make very high quality adapters with proper gauge.  If you have to use a adapter I suggest getting it from one of the makers on this forum.
QuintLeo
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November 04, 2015, 11:12:11 PM
 #27

If you have thick wire, it is OK to use the molex connector.


 Still have the issue with the limit of the PS on whatever +12v bus powers the "peripheral" connectors, and on an S7 you ARE talking about
 (1) Appx 400 watts or well over 30 AMPS per hash board, works out to about 13 AMPS per PCI-E if you're using all 3 of them per Bitmain specs.
 (2) limit of DO NOT POWER A SPECIFIC HASH BOARD FROM MORE THAN ONE PS.

 The issue isn't JUST the molex connector.
 In fact, it's more about limits of the Power Supply in this sort of case, though pulling over 6 amps through a peripheral-type Molex is marginal for reliability.
 It's not smart to assume the current draw will work out exactly equal, parallelling connectors tends to have a little imbalance on the contact resistances and makes the power draw somewhat uneven and makes those adapters even more marginal (to be fair, the imbalance would probably be on the order of 7 vs. 6 amps per connector *IF* both are making a good solid connection - but if one is NOT making a good solid connection, FRIED connector and probably fried S7 hashboard).

Quote

PCI-E 6-pin connector - up to 13 Amps per each wire (3 12V wires per connector) = theoretically up to 39 Amps but ATX spec limits PCIe-PEG connectors to 75 W (6.25 Amps).


 You have to derate the connectors used in a PCI-E connector by quite a bit.
 Molex only specs them for 8 AMPs each max = 24 amps per connector = 288 watts in a PCI-E 6-pin connector, due to heat retention by the connector itself.
 Even though the pins THEMSELVES are rated for 13 amps max that's a FREE AIR rating.

 (Yes, I read ALL of those specs a while back - it's where Spondoolies came up with it's 288 watt max limit per connector in the SP20 web interface).
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