[SOLVED] Wrong cable configuration may void warranty??

Aug 20, 2021
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Hello!

I had my first build a few years ago and the PSU only has 1 PCIE connector. I just got an 3080 which requires 3 PCIE cables. I want to use the current PSU for CPU + motherboard and another PSU for the 3080 only. But I read from Seasonic that it's "incorrect" and may void my warranty (https://seasonic.com/cable-config).

Can someone explain why please?
 

USAFRet

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Mar 16, 2013
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You need ONE power supply that can actually run the whole system.

Trying to use 2x, at least one of them is substandard, may well kill the whole system.

Why?
Hacked together wiring may introduce ground faults, or power feedback, or other bits of weirdness.



One and only one power supply.


Having said that....Can it be done?
Yeah, maybe. But if anything bad happens, Seasonic WILL void the warranty. And you may kill your shiny new GPU.
 
Reactions: rlindsberg

USAFRet

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Moderator
Mar 16, 2013
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You need ONE power supply that can actually run the whole system.

Trying to use 2x, at least one of them is substandard, may well kill the whole system.

Why?
Hacked together wiring may introduce ground faults, or power feedback, or other bits of weirdness.



One and only one power supply.


Having said that....Can it be done?
Yeah, maybe. But if anything bad happens, Seasonic WILL void the warranty. And you may kill your shiny new GPU.
 
Reactions: rlindsberg
Aug 20, 2021
10
0
10
0
You need ONE power supply that can actually run the whole system.

Trying to use 2x, at least one of them is substandard, may well kill the whole system.

Why?
Hacked together wiring may introduce ground faults, or power feedback, or other bits of weirdness.



One and only one power supply.


Having said that....Can it be done?
Yeah, maybe. But if anything bad happens, Seasonic WILL void the warranty. And you may kill your shiny new GPU.
I will use the new PSU for the whole system but I am just curious why Seasonic says "no CPU connectors" are wrong.

I will not hack any wirings but just saying a scenario that I use one PSU to power CPU and motherboard and another PSU to power GPU. Is this theoretically a hazard?
 
Aug 20, 2021
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List manufacturer/model names of your PSUs and RTX 3080.
RTX 3080 requires 750W PSU.
Sorry for forgetting this.
My old build is using EVGA BQ 500W. The new GPU is MSI RTX 3080 Suprim X and I plan to buy Seasonic Prime PX-750 750W for the whole system. I just wonder why using the latter PSU for GPU only is considered incorrect...
 

USAFRet

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Mar 16, 2013
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I will use the new PSU for the whole system but I am just curious why Seasonic says "no CPU connectors" are wrong.

I will not hack any wirings but just saying a scenario that I use one PSU to power CPU and motherboard and another PSU to power GPU. Is this theoretically a hazard?
Yes, that can be a HUGE hazard.

Using these items in a way not designed for can kill multiple things. Including YOU or your house.

Seasonic does not want to be responsible (warranty) for customer screwups.
 
Aug 20, 2021
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Yes, that can be a HUGE hazard.

Using these items in a way not designed for can kill multiple things. Including YOU or your house.

Seasonic does not want to be responsible (warranty) for customer screwups.

Oh... but could you explain why it may kill multiples things?
 

DSzymborski

Titan
Moderator
I will use the new PSU for the whole system but I am just curious why Seasonic says "no CPU connectors" are wrong.

I will not hack any wirings but just saying a scenario that I use one PSU to power CPU and motherboard and another PSU to power GPU. Is this theoretically a hazard?
As he just said, yes. A GPU powered by a supplementary PSU is still getting power from the first PSU (from the PCIe slot). That is a bad idea for the reasons already laid out.

And we've had the assumption that you were going to do this because you literally just said that you're going to do this.

It's perfectly understandable why SeaSonic doesn't want to be left holding the bag because you wanted to jury-rig a couple of PSUs together on your >$1000 GPU rather than run things properly.
 

USAFRet

Titan
Moderator
Mar 16, 2013
156,220
11,694
176,090
24,278
I will use the new PSU for the whole system but I am just curious why Seasonic says "no CPU connectors" are wrong.

I will not hack any wirings but just saying a scenario that I use one PSU to power CPU and motherboard and another PSU to power GPU. Is this theoretically a hazard?
It is "wrong", because it is not tested and verified by Seasonic.
Power can feed in the wrong direction. Potentially exploding one or the other PSU, or other components.

"I will not hack any wirings " ?
How would you wire them so that they both turn on at the same moment?
Hack....
 
Reactions: rlindsberg
Aug 20, 2021
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As he just said, yes. A GPU powered by a supplementary PSU is still getting power from the first PSU (from the PCIe slot). That is a bad idea for the reasons already laid out.

And we've had the assumption that you were going to do this because you literally just said that you're going to do this.

It's perfectly understandable why SeaSonic doesn't want to be left holding the bag because you wanted to jury-rig a couple of PSUs together on your >$1000 GPU rather than run things properly.
Ahh! I understand now, thanks!

You are right, I wanted to do it but I thought it would be better to ask here first. I really appreciate the help from you guys!
 

DSzymborski

Titan
Moderator
Ahh! I understand now, thanks!

You are right, I wanted to do it but I thought it would be better to ask here first. I really appreciate the help from you guys!
Yeah, no advantage except in emergency situations where someone absolutely has to run a GPU on a couple PSUs in some kind of work emergency or something. People do risk doing this when they're running on a dime and there are some workarounds to get the PSUs to turn on together, but it's usually with older equipment; anyone with a 3080 ought to be able to buy the equipment to safely run it and the PC safely!

Think of it like a sports car. You can't just buy the sports car, you gotta buy the insurance and factor in the additional maintenance too that you don't have with a family sedan.
 
Reactions: rlindsberg
Aug 20, 2021
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Yeah, no advantage except in emergency situations where someone absolutely has to run a GPU on a couple PSUs in some kind of work emergency or something. People do risk doing this when they're running on a dime and there are some workarounds to get the PSUs to turn on together, but it's usually with older equipment; anyone with a 3080 ought to be able to buy the equipment to safely run it and the PC safely!

Think of it like a sports car. You can't just buy the sports car, you gotta buy the insurance and factor in the additional maintenance too that you don't have with a family sedan.
Thank you again for the explanation!
 
Aug 20, 2021
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I would void Seasonic Prime with a RTX 3080 because of issues. Get a 850w Corsair RMx 2018/2021 or HX Platinum, Fractal Design ION+ 860w or Super Flower Leadex III Gold 850w instead.
I like Corsair a bit more so I think I will get one from them. Right now a RM850 2019 costs 990 SEK (114 USD) and a RM850X 2018 costs 1199 SEK (138 USD). I heard that RMx is better but does it justify the price difference?
 

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