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Author Topic: Power Supply Ports  (Read 196 times)
NCarter84 (OP)
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January 11, 2018, 09:14:06 PM
 #1

Howdy Folks! I'm in the process of building out my very 1st rig!

Today, I purchased a new PSU (Corsair RM 750x) on the back of the power supply where you plug your cables in, I had a question about those ports.

The ones that are labeled "Peripheral & Sata" can I plug in another PCIe cable with two 6+2pin connector? ( Link to product: http://www.corsair.com/en-us/type-4-sleeved-black-pci-e-cable-with-pigtail-connector-and-capacitors-for-type-4-psu )

This rig will have a max of (3) RD570 GPUs with just the bare amount of hardware (Mobo,RAM, CPU, HDD) to run it.

Thanks in advance!

-N

leonix007
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January 11, 2018, 11:32:26 PM
 #2

Howdy Folks! I'm in the process of building out my very 1st rig!

Today, I purchased a new PSU (Corsair RM 750x) on the back of the power supply where you plug your cables in, I had a question about those ports.

The ones that are labeled "Peripheral & Sata" can I plug in another PCIe cable with two 6+2pin connector? ( Link to product: http://www.corsair.com/en-us/type-4-sleeved-black-pci-e-cable-with-pigtail-connector-and-capacitors-for-type-4-psu )

This rig will have a max of (3) RD570 GPUs with just the bare amount of hardware (Mobo,RAM, CPU, HDD) to run it.

Thanks in advance!

-N



No, PCI-e has different pins and it wont Fit to SATA/Peripherals, you can't put in there Physically

http://www.corsair.com/en-us/rmx-series-rm750x-750-watt-80-plus-gold-certified-fully-modular-psu

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This rig will have a max of (3) RD570 GPUs with just the bare amount of hardware (Mobo,RAM, CPU, HDD) to run it.

you can install more than 3 NVIDIA 1060 GPU on this PSU.
tg88
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January 12, 2018, 11:06:51 AM
 #3

With this psu you can connect 4 gpus (mid-range) without problems.
NCarter84 (OP)
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January 12, 2018, 01:35:02 PM
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I'd only want to do 3 GPU... The goal is my 1st rig to run (3) RX570s....

Would I just use a split off one of the 8 pin ports? And create 2 8's from 1?
inter23
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January 12, 2018, 01:54:58 PM
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Howdy Folks! I'm in the process of building out my very 1st rig!

Today, I purchased a new PSU (Corsair RM 750x) on the back of the power supply where you plug your cables in, I had a question about those ports.

The ones that are labeled "Peripheral & Sata" can I plug in another PCIe cable with two 6+2pin connector? ( Link to product: http://www.corsair.com/en-us/type-4-sleeved-black-pci-e-cable-with-pigtail-connector-and-capacitors-for-type-4-psu )

This rig will have a max of (3) RD570 GPUs with just the bare amount of hardware (Mobo,RAM, CPU, HDD) to run it.

Thanks in advance!

-N



No, PCI-e has different pins and it wont Fit to SATA/Peripherals, you can't put in there Physically

http://www.corsair.com/en-us/rmx-series-rm750x-750-watt-80-plus-gold-certified-fully-modular-psu

Quote
This rig will have a max of (3) RD570 GPUs with just the bare amount of hardware (Mobo,RAM, CPU, HDD) to run it.

you can install more than 3 NVIDIA 1060 GPU on this PSU.
I did 6 1060s on this psu with no issues lol. 570 wise the draw is slightly higher so 4 is safe. Yes u can connect 2 gpus from one cable from the psu not an issue.
Vann
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January 12, 2018, 01:55:40 PM
 #6

Splitting an 8-pin PCI-E connector to dual 8-pins is not recommended. That's a good way to overload the PSU cable and rail with up to 300W. That PSU has 4 PCI-E ports. With 3 cards and 6-pin risers, you can use 3 PCI-E ports for the VGA 8-pins and use a 8-pin to dual 6-pin splitter cable to power two of the the 6-pin risers. The last riser can be powered with a 4-pin molex to 6-pin adapter cable.

https://www.aliexpress.com/item/20CM-Black-Sleeved-8-Pin-PCI-E-GPU-to-Dual-8-6-2-Pin-Splitter-PC/32688175733.html?

https://www.aliexpress.com/item/Carprie-New-ATX-IDE-Molex-Power-Dual-4-To-6-Pin-PCI-Express-PCIe-Video-Card/32820268682.html?
inter23
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January 12, 2018, 02:03:58 PM
Last edit: January 12, 2018, 02:16:03 PM by inter23
 #7

Splitting an 8-pin PCI-E connector to dual 8-pins is not recommended. That's a good way to overload the PSU cable and rail with up to 300W. That PSU has 4 PCI-E ports. With 3 cards and 6-pin risers, you can use 3 PCI-E ports for the VGA 8-pins and use a 8-pin to dual 6-pin splitter cable to power two of the the 6-pin risers. The last riser can be powered with a 4-pin molex to 6-pin adapter cable.

https://www.aliexpress.com/item/20CM-Black-Sleeved-8-Pin-PCI-E-GPU-to-Dual-8-6-2-Pin-Splitter-PC/32688175733.html?

https://www.aliexpress.com/item/Carprie-New-ATX-IDE-Molex-Power-Dual-4-To-6-Pin-PCI-Express-PCIe-Video-Card/32820268682.html?
This is safe but to me thats way below what this psu can deliver. There's 3 pcie slots and a max power rating of 750w/62.5A at 12v, so thats 250w from each pcie port safely which still has room for overdraw. using 2x570s with undervolt from one output is not an issue based on corsair standards. by numbers it can even go to 3

You should be more careful about the riser connection though, each riser can draw max 75w on 6pins and the per +12v cable draw limit is ard 54w (only 1 cable for sata but 3 for pcie, thus the ability to split to 2 gpus). so i would split the riser cables and plug into 3 separate peripheral and sata ports. 2 risers to 1 port would be hot, 3 would last u below 1 week before it melts at the ports.
Vann
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January 12, 2018, 02:32:19 PM
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Splitting an 8-pin PCI-E connector to dual 8-pins is not recommended. That's a good way to overload the PSU cable and rail with up to 300W. That PSU has 4 PCI-E ports. With 3 cards and 6-pin risers, you can use 3 PCI-E ports for the VGA 8-pins and use a 8-pin to dual 6-pin splitter cable to power two of the the 6-pin risers. The last riser can be powered with a 4-pin molex to 6-pin adapter cable.

https://www.aliexpress.com/item/20CM-Black-Sleeved-8-Pin-PCI-E-GPU-to-Dual-8-6-2-Pin-Splitter-PC/32688175733.html?

https://www.aliexpress.com/item/Carprie-New-ATX-IDE-Molex-Power-Dual-4-To-6-Pin-PCI-Express-PCIe-Video-Card/32820268682.html?
This is safe bot to me thats way below what this psu can deliver. There's 4 pcie slots and a max power rating of 750w/62.5A at 12v, so thats 187.5w from each pcie port safely with should be much higher. using 2 570s with undervolt from one output is not an issue based on corsair standards.

Except that it's not. For one thing the total capacity of the PSU has nothing to do with the maximum rating of the individual ports or the cables. RX 570's even undervolted, mining Equihash or dual mining can easily use 100-110W each from the VGA 8-pin. In the best case, that's 200W+ from one cable. Depending on the gauge of the wire used for the cable you would be far exceeding the the rated capacity of 18 AWG cable, which is 10A or 120W max at 12V. If 16 AWG cables are used, you would still be drawing over 200W from one PSU connector and it's NOT safe, especially for use in a mining rig under constant load 24/7.

http://www.rowand.net/shop/tech/wirecapacitychart.htm

inter23
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January 12, 2018, 03:10:29 PM
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Splitting an 8-pin PCI-E connector to dual 8-pins is not recommended. That's a good way to overload the PSU cable and rail with up to 300W. That PSU has 4 PCI-E ports. With 3 cards and 6-pin risers, you can use 3 PCI-E ports for the VGA 8-pins and use a 8-pin to dual 6-pin splitter cable to power two of the the 6-pin risers. The last riser can be powered with a 4-pin molex to 6-pin adapter cable.

https://www.aliexpress.com/item/20CM-Black-Sleeved-8-Pin-PCI-E-GPU-to-Dual-8-6-2-Pin-Splitter-PC/32688175733.html?

https://www.aliexpress.com/item/Carprie-New-ATX-IDE-Molex-Power-Dual-4-To-6-Pin-PCI-Express-PCIe-Video-Card/32820268682.html?
This is safe bot to me thats way below what this psu can deliver. There's 4 pcie slots and a max power rating of 750w/62.5A at 12v, so thats 187.5w from each pcie port safely with should be much higher. using 2 570s with undervolt from one output is not an issue based on corsair standards.

Except that it's not. For one thing the total capacity of the PSU has nothing to do with the maximum rating of the individual ports or the cables. RX 570's even undervolted, mining Equihash or dual mining can easily use 100-110W each from the VGA 8-pin. In the best case, that's 200W+ from one cable. Depending on the gauge of the wire used for the cable you would be far exceeding the the rated capacity of 18 AWG cable, which is 10A or 120W max at 12V. If 16 AWG cables are used, you would still be drawing over 200W from one PSU connector and it's NOT safe, especially for use in a mining rig under constant load 24/7.

http://www.rowand.net/shop/tech/wirecapacitychart.htm


This I agree as wire used is very impt, got to consider cable load and psu load simultaneously. So I always make sure the cables are of quality build. As the op is stating corsair, in my own experience cables are of no issues. Been using corsair especially the hx1200 extensively, abusively at times but they held up well. Cool

"Depending on the gauge of the wire used for the cable you would be far exceeding the the rated capacity of 18 AWG cable, which is 10A or 120W max at 12V."
And dont forget, pcie using 3 +12v wires not 1. So theres no issue if u calculate it right.
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January 12, 2018, 03:41:45 PM
 #10

By your calculations hes fine.

There are three +ve lines in a 6/8 pin PCI-e power line.

10A - 12v = 120W
120W x 3 - 360W


Vann
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January 12, 2018, 04:07:19 PM
 #11

The maximum PCI-E specification of a PCI-E 8-pin connector is 150W, not 360W. The maximum specification for a 6-pin PCI-E connector is 75W.




The PCI-E specification is not just based on wire gauge. It's also based on power delivery. Wires and connectors have resistance. The voltage drop and power dissipation as heat increase as you increase the current. The resistance of connectors also tends to increase as they are plugged and unplugged so after enough uses they can overheat and even melt when passing a large current. Which is why it's NOT safe to overload a 8-pin connector with more than the rated specification. ESPECIALLY for a mining rig under constant high load 24/7.
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January 12, 2018, 04:25:33 PM
Last edit: January 12, 2018, 04:38:39 PM by inter23
 #12

The maximum PCI-E specification of a PCI-E 8-pin connector is 150W, not 360W. The maximum specification for a 6-pin PCI-E connector is 75W.


https://image.ibb.co/i495Cw/Screenshot_from_2017_12_02_13_05_36.png

The PCI-E specification is not just based on wire gauge. It's also based on power delivery. Wires and connectors have resistance. The voltage drop and power dissipation as heat increase as you increase the current. The resistance of connectors also tends to increase as they are plugged and unplugged so after enough uses they can overheat and even melt when passing a large current. Which is why it's NOT safe to overload a 8-pin connector with more than the rated specification. ESPECIALLY for a mining rig under constant high load 24/7.

Yes that is rated to the pcie pins including the socket and connectors. I'm saying wire wise there is no issue for 1 8 pin into 2 8pin. 150w limit is to the Socket on gpu side which is still draw of 1 gpu, on psu side the 150w limit is not true. Howevery I do agree that through the entire connection, the highest stress point is at the psu 8pin connection sockets. If any overdraw happens this is where it is most likely to heat up first.

Brand of PSu is very important, that why we are paying more for the corsairs, all the ratings are standards to abide to at minimum but good brands always surpass them by quite abit. I have tried running the hx1200 at 1400w for almost 3 months 24/7 ambient temp at 28c with no issues. Hence the confidence for their build. Of cos this does not apply to any other brands.
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January 12, 2018, 05:16:41 PM
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The maximum PCI-E specification of a PCI-E 8-pin connector is 150W, not 360W. The maximum specification for a 6-pin PCI-E connector is 75W.




The PCI-E specification is not just based on wire gauge. It's also based on power delivery. Wires and connectors have resistance. The voltage drop and power dissipation as heat increase as you increase the current. The resistance of connectors also tends to increase as they are plugged and unplugged so after enough uses they can overheat and even melt when passing a large current. Which is why it's NOT safe to overload a 8-pin connector with more than the rated specification. ESPECIALLY for a mining rig under constant high load 24/7.

Yes that is rated to the pcie pins including the socket and connectors. I'm saying wire wise there is no issue for 1 8 pin into 2 8pin. 150w limit is to the Socket on gpu side which is still draw of 1 gpu, on psu side the 150w limit is not true. Howevery I do agree that through the entire connection, the highest stress point is at the psu 8pin connection sockets. If any overdraw happens this is where it is most likely to heat up first.

Brand of PSu is very important, that why we are paying more for the corsairs, all the ratings are standards to abide to at minimum but good brands always surpass them by quite abit. I have tried running the hx1200 at 1400w for almost 3 months 24/7 ambient temp at 28c with no issues. Hence the confidence for their build. Of cos this does not apply to any other brands.

PSU rail ratings differ between models from the same brand and even different VGA ports on the same PSU. e.g. EVGA specifically says in their G2/P2 manuals the 8-pin with 6-pin pigtail cables should only be used in the last two VGA ports.



Physics doesn't change because you pay more for a PSU. The fact is by running a PSU over it's rated capacity you are greatly reducing the efficiency and lifespan of the PSU, which is a bad idea for a mining rig. Your experience also doesn't change the fact that you and pulling more watts through a connector than it was intended to deliver. Your experience with one PSU brand also doesn't mean others have that same experience.

https://www.youtube.com/watch?v=PXoPFPqU3Y8&feature=youtu.be&t=3798
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