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Author Topic: Can i power a GPU (3060ti) using a MOLEX to 8-Pin PCIE adapter?  (Read 314 times)
miner29
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January 10, 2021, 04:30:24 PM
 #21

It's better to buy a powerpack with gpu cables and not this one, I have few of them when I was building my rigs in 2017 because they are very cheap and I ended up burning some wires up, thank God as was not away from home at the time, if not I'd have cause big damages to my home then
There is nothing wrong using that cable, I've bought some brand new graphics cards that has same cable in the package, if the cable isn't safe they won't put on in the package, I got those cables from Nvidia cards the most, I believe they are safe

The molex to 6 pin is good for 75w.  If using 2 molex on a single chain then max is 156w.

The 6 pin to dual 8 pins is max 216w....but the dual 8s can pull 288w.

The link i provided spells it all out.  Exceed the ratings and its on you.  Also note that all wiring / plugs / crimps are not equal.  If any of those are skimped on your limits only decrease.


What about SATA connector ?
Personally had somme problems with SATA-PIN6 connectors - somme of my 5700 are melting it - i`m talking about powering risers.

Definitely a bad idea.  SATA is good for 54w total (1 sata connector on the chain).  6 pin PCI can provide 216W....so using the SATA to PCI 6pin can easily draw 4X the power that sata can handle.  I dont use them...that is asking for trouble.    They make converter for almost any direction you can imagine, but some are definitely bad ideas. Respect the watt limit.  
JayDDee
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January 10, 2021, 05:30:35 PM
 #22

They make converter for almost any direction you can imagine, but some are definitely bad ideas.

How about ATX CPU 8 pin -> 2x VGA 6+2 pin? I see converters for that. Seems like it could be the best way to add
VGA capacity if the PSU has 2 8-pin CPU cables.

miner29
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January 10, 2021, 06:16:18 PM
 #23

They make converter for almost any direction you can imagine, but some are definitely bad ideas.

How about ATX CPU 8 pin -> 2x VGA 6+2 pin? I see converters for that. Seems like it could be the best way to add
VGA capacity if the PSU has 2 8-pin CPU cables.

This can handle a total of what the single 8pin can provide from the PSU.  So total watts safe is 288watts max for both of the 6+2 off the 8pin.   Problem arises if you gpus for whatever reason draw the max which means 526W trying to go down a 288watt wire.....  That is the risk.  Even is each gpu pulls 150w....you would risk melting the wires or even burning.

All this info is on the link i provided earlier in this thread...with handy pics. 
JayDDee
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January 10, 2021, 07:30:30 PM
 #24

They make converter for almost any direction you can imagine, but some are definitely bad ideas.

How about ATX CPU 8 pin -> 2x VGA 6+2 pin? I see converters for that. Seems like it could be the best way to add
VGA capacity if the PSU has 2 8-pin CPU cables.

This can handle a total of what the single 8pin can provide from the PSU.  So total watts safe is 288watts max for both of the 6+2 off the 8pin.   Problem arises if you gpus for whatever reason draw the max which means 526W trying to go down a 288watt wire.....  That is the risk.  Even is each gpu pulls 150w....you would risk melting the wires or even burning.

All this info is on the link i provided earlier in this thread...with handy pics. 

Are you sure about that? The link you referenced didn't mention anything about using the CPU port and I haven't
found any info elsewhere except that adapters for it exist.

It seems like a a better workaround than using either Molex or Sata. I wonder why it hasn't come up before.

bobben2
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January 10, 2021, 07:44:32 PM
 #25

I have 2 x 2 Molex to 8 pin PCI powering my single  MSI 3060TI Ventus 2x and it is working fine.  The reason for this arrangement is the rather modest PSU at the moment, a Corsair VX 450 Watts rated.
Make sure your molexes are connected to separate strands from the PSU if possible.

Fellow miners, get your thens and thans in order and help other forum readers understand what you are writing. Remember the grammar basics:  B larger THAN A (comparator operator). If something THEN ....
miner29
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January 10, 2021, 11:38:16 PM
 #26

They make converter for almost any direction you can imagine, but some are definitely bad ideas.

How about ATX CPU 8 pin -> 2x VGA 6+2 pin? I see converters for that. Seems like it could be the best way to add
VGA capacity if the PSU has 2 8-pin CPU cables.

This can handle a total of what the single 8pin can provide from the PSU.  So total watts safe is 288watts max for both of the 6+2 off the 8pin.   Problem arises if you gpus for whatever reason draw the max which means 526W trying to go down a 288watt wire.....  That is the risk.  Even is each gpu pulls 150w....you would risk melting the wires or even burning.

All this info is on the link i provided earlier in this thread...with handy pics.  

Are you sure about that? The link you referenced didn't mention anything about using the CPU port and I haven't
found any info elsewhere except that adapters for it exist.

It seems like a a better workaround than using either Molex or Sata. I wonder why it hasn't come up before.

i missed the cpu part read it as pci....doh..

If you have dual cpu leads which a lot of the bigger units do have...you can get a cpu to pcie 8pin to 8pin plug.  Just corrects the wiring and physical plug shape.  Check your psu to see what its rated at and as always dont exceed that.  
cudapop
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January 12, 2021, 04:12:47 PM
 #27

So it's time to turn on my rig again but i've run out of working PSUs.

I'm looking to use a molex to 8-pin PCIE adapter like this one in the image below.
If the 3060ti only consumes around 120-150w undervolted do you guys think it's safe to use this?

Be sure to check the AWG rating of the wires used in the adapter (you can read the AWG rating printed directly on the insulator covering each yellow/black wire of the adapter). If you're pulling 150 watts then you are asking each molex (i.e. it's associated 12V line) to provide 75 watts each. This means a current draw of 6.25 amps per 12V molex line. This would require a wire rated for AWG 22 or better (in AWG terms a better rating means a lower AWG number which corresponds to a higher amperage capacity of the wire). So be sure the wires attached to the adapter have "AWG 22" printed on them.

The connector itself (ie. the plastic housing and metal flanges/probes are rated for 8 amps for the typical molex connector, so they can handle the 75 watts per molex.

See the following AWG chart for wire amperage capacities (in the column labeled "Maximum amps for chassis wiring"): https://www.powerstream.com/Wire_Size.htm

https://www.gpuminingresources.com/p/psu-cables.html

All is answered there.  Respect the wattage limits or you may well burn something up or everything down.

Note that the "www.gpuminingresources.com" guide is assuming wire AWG gauges which are maxed to match the rating of the connector. For example, the 8-pin PCIe is shown to support 288 watts which, with three 12V circuits, means a draw of 8 amps per circuit hence requiring AWG 21 gauge (or better) wires.

So be sure to check that the wires used in the actual adapter are rated accordingly to the amperage you are expecting to draw through them.

---

Lastly, as others have pointed out, be sure to connect the dual molex connectors to separate cables from the PSU. If you connect both molex connectors to a single "daisy-chained" cable from the PSU then you are asking the single 12V pin on that cable to provide the entire 150W you're drawing, which means around 12.5 amps current draw on that single pin, hence requiring a PSU cable wire rated at AWG 19.
miner29
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January 12, 2021, 04:46:41 PM
 #28

I recommend after the rig has been running to do the hand test...using your hand touch the jackets on the power cables supply boards and risers etc.  If they are warm be concerned.  There should be not too much heat coming off them.  If they are warm or jackets are soft due to temp...be concerned. 
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