Question Daisy chaining RTX 3080 - dangerous?

xollextor

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Jul 28, 2019
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This is a prebuilt PC since I have almost no knowledge on how to mount a PC together, I've been using it for about a month without a single issue so far but today I just noticed that it is daisy chained

PSU: Corsair TX850M Gold
GPU: Gigabyte RTX 3080 Gaming OC (Stock) 8*2 pins

My PSU only has one PCI-E (6+2) output that I presume is the one connected to the GPU and then split into the two pins

I looked into how much GPU draws power (HWiNFO64) and it totals on a little over 320w with each 8-pin input mostly drawing over 130 (one maxed at 110w while the other's maxed 130w)

I saw many topics saying that this could be dangerous and a potential fire hazard and can quickly damage both GPU and PSU while the cables get very hot, but I also saw others saying it's practical and perfectly safe IF the PSU is of quality.

I'm honestly lost, I couldn't find a clear answer and I certainly don't want to blow my GPU up because it wasn't easy to find and cheap to buy.

Is this safe? I haven't noticed any problems yet, clock speeds seem to hit where they are supposed to and I had 0 games crash on me just yet and no performance issues, everything's stable

Here's a picture to demonstrate how the power cables are set up:
 
Rule of thumb is if a card has 2 power connectors it should have 2 PCI-E power cables.
Does not look as pretty through the window ,but much better for your card and power supply.
The TX 850 is a good upper mid range power supply. BUT over time the cable will slowly degrade from heating cycles. Especially long gaming sessions.
Your power supply should have at least 2 of those cables, most quality 850 watt models have 4.
 

RTX 2080

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This is a prebuilt PC since I have almost no knowledge on how to mount a PC together, I've been using it for about a month without a single issue so far but today I just noticed that it is daisy chained

PSU: Corsair TX850M Gold
GPU: Gigabyte RTX 3080 Gaming OC (Stock) 8*2 pins

My PSU only has one PCI-E (6+2) output that I presume is the one connected to the GPU and then split into the two pins

I looked into how much GPU draws power (HWiNFO64) and it totals on a little over 320w with each 8-pin input mostly drawing over 130 (one maxed at 110w while the other's maxed 130w)

I saw many topics saying that this could be dangerous and a potential fire hazard and can quickly damage both GPU and PSU while the cables get very hot, but I also saw others saying it's practical and perfectly safe IF the PSU is of quality.

I'm honestly lost, I couldn't find a clear answer and I certainly don't want to blow my GPU up because it wasn't easy to find and cheap to buy.

Is this safe? I haven't noticed any problems yet, clock speeds seem to hit where they are supposed to and I had 0 games crash on me just yet and no performance issues, everything's stable

Here's a picture to demonstrate how the power cables are set up:
I have seen two main schools of thought with this:

A. You risk damaging something, so you're better off using two separate cables. It's probably a good idea no matter what.

B. If the PSU is the appropriate wattage for your GPU and shipped with the cables in question, then obviously it was designed to be plugged in this way. Don't overthink it.

I personally agree most with option B. And anyway, in your situation if you wanted to plug in two separate cables, you'd need to buy a new power supply (seeing as how yours comes with only one PCIe power port). So long as your PSU is of good quality and has the proper wattage for your build, it seems like more trouble than it's worth to me. Different people will have different opinions though depending on their experiences and what they think seems to be a good idea or not.
 

xollextor

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Jul 28, 2019
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Rule of thumb is if a card has 2 power connectors it should have 2 PCI-E power cables.
Does not look as pretty through the window ,but much better for your card and power supply.
The TX 850 is a good upper mid range power supply. BUT over time the cable will slowly degrade from heating cycles. Especially long gaming sessions.
Your power supply should have at least 2 of those cables, most quality 850 watt models have 4.
it seems i only have 6+2 pci-e and 4+4 cpu outputs in my psu (as shown in the picture i linked), ive seen - though very rarely - tech channels use this cable arrangement, i've seen LTT use this daisy chain setup but that was on a RTX 2080 which draws less power than RTX 3080
 

xollextor

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Jul 28, 2019
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I have seen two main schools of thought with this:

A. You risk damaging something, so you're better off using two separate cables. It's probably a good idea no matter what.

B. If the PSU is the appropriate wattage for your GPU and shipped with the cables in question, then obviously it was designed to be plugged in this way. Don't overthink it.

I personally agree most with option B. And anyway, in your situation if you wanted to plug in two separate cables, you'd need to buy a new power supply (seeing as how yours comes with only one PCIe power port). So long as your PSU is of good quality and has the proper wattage for your build, it seems like more trouble than it's worth to me. Different people will have different opinions though depending on their experiences and what they think seems to be a good idea or not.
That's what I thought too, there is even an extra 100w headroom for the recommended wattage for the RTX 3080, though I have no problem replacing whole PSU I just want a long lasting PC that would stay on for the next 5-6 years
 

InvalidError

Titan
Moderator
A properly made cable can handle 13A per pin so a single 8-pin AUX cable which has three actual 12V pins would be able to push nearly 450W while still within the high-current Molex MiniFitJr spec. The only reason the PCI-SIG limited AUX cables to 150W per plug is to make it more difficult for PSU manufacturers to screw up things badly enough to become a concern at least wiring-wise such as by using low-current (8-9A) spec pins.
 
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xollextor

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A properly made cable can handle 13A per pin so a single 8-pin AUX cable which has three actual 12V pins would be able to push nearly 450W while still within the high-current Molex MiniFitJr spec. The only reason the PCI-SIG limited AUX cables to 150W per plug is to make it more difficult for PSU manufacturers to screw up things badly enough to become a concern at least wiring-wise such as by using low-current (8-9A) spec pins.
Sorry for the blurry picture, phone was low battery so I had to use lightbulb for illumination, anyways I found this piece of information on the manual, I'm nowhere near a technician or electrician but I thought I should mention it, could be useful since it mentions "12A", sorry again if it's irrelevant.

EDIT: I found the manual in PDF form by Corsair: https://www.corsair.com/corsairmedia/sys_master/productcontent/TXM_Manual.pdf
 
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xollextor

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Upon hours and hours of research I found it has a lot to do with wire gauge, and a 16awg 8-pin can draw as high as 400w and is relatively safe whereas 18awg can only draw 288w and has high risk of causing damage, I've looked everywhere and have only found 1 single review about the PSU that I have where it claims the 8 pin to 2x 6+2 "6+2 pin PCI-e, 6+2 pin PCI-e" is 16awg which is safe from what I understood, but I'm not sure how true is this because the aftermarketed ones off of ebay and newegg for TX-M all seem to be 18awg

"As stated, this unit runs a mix of ribboned and sleeved cables. Here are the PCI-e cables, and they are 16 gauge. Not necessary for this size of unit, but nice to see."
I truly hope someone can clarify this for me, I want to know if the PCI-e wire gauge for the PSU I have is really 16 and if so is it still safe.

Link to the Corsair TX850M review: Link to PSU Manual:
 
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InvalidError

Titan
Moderator
Upon hours and hours of research I found it has a lot to do with wire gauge, and a 16awg 8-pin can draw as high as 400w and is relatively safe whereas 18awg can only draw 288w and has high risk of causing damage,
#18 wiring in a wiring cabinet such as a PC case is good for up to 16A, which is over 170W per wire or 500W for an AUX cable that has 3x12V pins. Even the AWG table for insulated walls rates #18 as good enough for 10A which would be 360W for 3x12V wires.

The only benefit you get from #16 over #18 is ~50mV less voltage droop on cables at full load which the GPU's VRM should be perfectly capable of coping with under normal circumstances. Unlikely to make any difference unless you are pushing stability limits.
 

xollextor

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4+4pin connector is for cpu power only. Not compatible with pcie power. It physically doesn't fit.
i meant the PSU output connector, can both supply GPU? because I plugged the second cable since everyone seemed too skeptical about one cable supplying over 300w of power, I'm now running 2 separate cables (i messed up a bit cable management but it was worth it i guess)
 

tecmo34

Administrator
Moderator
the only 8 pin output connectors on the PSU are PCI-e 6+2 and CPU 4+4

can I plug the gpu power cable into the 4+4 or it doesn't matter?
Where is says 6+2 PCI-E & 4+4 CPU on the PSU, this means you can plug in either two 6+2 PCI-E cables to support your GPU (recommended) or you could plug in one 6+2 PCI-E cable for a GPU and a second 4+4 CPU pin for your motherboard, as some have a 8-pin and another 4 (or 8) pin connector for extreme overclocking to give the motherboard more power.



You will want to use these two slots for your two PCI-E cables for the GPU.
 
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4+4pin connector goes into motherboard and powers cpu.
6+2pin connector goes into graphics card.
You can't mix them. They are physically different and not interchangeable.
You actually can plug the 4+4 into the 6+2 on a GPU when you flip it. There are many people who don't pay attention when building or upgrading their computers for the first time and they do make the mistake of plugging in the wrong cable.
 

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