Was I supposed to be using one PCIe cable per GPU connector this entire time?

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Rev. Night

[H]ard|Gawd
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I have a Corsair RMx 750x and I recently bought a 3080 that comes with a triple power connector (3 connectors of 2x8 pin). For all previous cards (including my 7900xtx), they have used a double connector of 2x8pin. I always thought that since the PCIe cable comes with that double head at the end, that only a single pcie cable was needed to power the GPU. I read through google, and saw several articles/message boards saying that this is bad, each connector needs its dedicated pcie cable. Others said I'm fine

If true, wtf do I do with this 2nd header of each pcie cable?
If not true, would 2 cables to power this 3080 be fine? One cable that utilizes both headers, the second cable would only utilize one header
 
High end 30 series Nvidia cards were quite the power problem for some PSUs. Yes, the best practice for them was to use separate PCIE power cables for each connection, not a daisy chained one.

The 3080 wasn't as bad as the 3090 in regards to power issues, so you might be OK.
 
Rev. Night said:
If true, wtf do I do with this 2nd header of each pcie cable?
If not true, would 2 cables to power this 3080 be fine? One cable that utilizes both headers, the second cable would only utilize one header
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i used etape to hide mine. tucked it behind/under the one in use and taped it up.
yes.
 
glad I kept all my psu cables in the nice bag it came with. I have exactly 2 surplus. Just as easy for me to put these into the case just to guarantee.
 
I used 2 cables from my Seasonic Prime 1000 on my 3 connector OC'd 3080. No problems at all. Even my 4090 is using 2 cables to the 4-8 pin adapter. I will note that the official Seasonic 12VHPWR cable also comes from 2 PCIe connectors on the PSU, so it's rated for it. I'm sure Corsair designed things right so that using the double connector is still safe.
 
Grebuloner said:
I used 2 cables from my Seasonic Prime 1000 on my 3 connector OC'd 3080. No problems at all. Even my 4090 is using 2 cables to the 4-8 pin adapter. I will note that the official Seasonic 12VHPWR cable also comes from 2 PCIe connectors on the PSU, so it's rated for it. I'm sure Corsair designed things right so that using the double connector is still safe.
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It will largely depend on the cable quality and the +12V rail on the unit. 18 AWG PCI-E cables can generally go up to 25A before having issues even though the specification calls for half that, and I would have no qualms with the Seasonic cable given their quality. My past experience with CWT units from Corsair like the RMx 750x I would give me doubts, though.
 
I was using my 3080 Ti with a daisy chain for quite some time and never had any issues on my Seasonic 850W gold PSU. Later I did replace it with individual connectors just in case, though. The GPU is still working just fine in another room, doing Stable Diffusion 24/7, on the same PSU. I think you'll be fine. The Seasonic connectors are very thick and high quality.

LigTasm said:
I could type it, but the pros describe it better. TL,DR: its not going to hurt anything on a 3080.

Link starts where he describes why you hear 150W limit for 8-pin connectors sometimes.


View: https://youtu.be/p0fW5SLFphU?t=321
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Unrelated to the topic but related to this video. I'm definitely on the same page with him. I have always thought the 12VHPWR connector was stupid. That was a large part of why I decided to get a new case and make this topic: https://hardforum.com/threads/not-sure-if-a-case-like-this-exists.2031522/

I wanted a case that was wide enough to accommodate the 12VHPWR connector without bending before the length that they recommend, and it's been great for that. My 4090 has been running 24/7 and often doing Stable Diffusion work at the same time as gaming (so 100% maxed load at all times) while using the OEM 4x8pin adapater, and I haven't had any reboots or issues. The Hybrid AIO design is also great for being able to tie down the cable and eliminate any socket stress. But god this shit makes me nervous...
 
Armenius said:
It will largely depend on the cable quality and the +12V rail on the unit. 18 AWG PCI-E cables can generally go up to 25A before having issues even though the specification calls for half that, and I would have no qualms with the Seasonic cable given their quality. My past experience with CWT units from Corsair like the RMx 750x I would give me doubts, though.
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what bad experiences with the RM 750x have you had? I have had 2 of them in my htpc and gaming pc for the past few years, nothing but good things to say. No power issues, idle fan stop and then very quiet when its on.
 
Rev. Night said:
what bad experiences with the RM 750x have you had? I have had 2 of them in my htpc and gaming pc for the past few years, nothing but good things to say. No power issues, idle fan stop and then very quiet when its on.
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Not the 750x specifically, but another CWT rebranded power supply (Corsair HX 850). I always had power gremlins with it that I could never narrow down. When I replaced it with a 750W Seasonic unit the gremlins went away. One particularly nasty gremlin was certain graphic loads tripping the OCP and shutting the PC down when my limited testing showed power to otherwise be fine. I was only pulling 400-500W from it at the time when the OCP would trip.
 
interesting. Ive never had any problems with my corsair PSUs

Because I already had the extra cable, I went ahead and did 3 cables into the 3080. Cant hurt, might help
 
Corsair type 4 ports are rated for 300w each and cables should be up to the task as well. Of course better to use more cables if possible, but never had an issue with using a daisy chain cable from corsair. Granted I mostly have had AX series on the tougher loads, but have also used rmx and hx series on lighter loads (200w or so GPUs).
 
evhvis said:
Corsair type 4 ports are rated for 300w each and cables should be up to the task as well. Of course better to use more cables if possible, but never had an issue with using a daisy chain cable from corsair. Granted I mostly have had AX series on the tougher loads, but have also used rmx and hx series on lighter loads (200w or so GPUs).
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I think the OEM on the lower rated AX units is Seasonic. The higher rated ones are Flextronics.
 
The power spikes on Ampere suck, so it's usually best to default to one cable per connection and not daisy chain. That said, 3080 is not as high power draw as 3090 or 3090 Ti, so you may be ok. I'd at least check the power ratings for your cables and that should tell you if it's ok. But for me, I'd rather just play it safe.

What you absolutely should not do though is buy a 3090 Ti or 4090, daisy chain cables to adapter and then run a 660W BIOS on it.
 
Armenius said:
I think the OEM on the lower rated AX units is Seasonic. The higher rated ones are Flextronics.
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The AX 850 and AX 1000 that were sold in 2020 were afaik based on Seasonic TX.

I have an AX 850 bought November 2020 because the AX 1000 was out of stock and had 3080+5900x in the transit or already arrived and didn't want to run those on a 9 year old AX 850 unit plus I needed the old one for another build.
 
Sir Beregond said:
The power spikes on Ampere suck, so it's usually best to default to one cable per connection and not daisy chain. That said, 3080 is not as high power draw as 3090 or 3090 Ti, so you may be ok. I'd at least check the power ratings for your cables and that should tell you if it's ok. But for me, I'd rather just play it safe.

What you absolutely should not do though is buy a 3090 Ti or 4090, daisy chain cables to adapter and then run a 660W BIOS on it.
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The native cable is not that expensive and uses 2 PCI-e ports on the PSU so better to not use an adapter at all.
 
I have an EVGA 3080 FTW3 Ultra since new and I use two cables (one being daisy chained) for the three 8 pin plugs. There SHOULD be no issue doing that... My psu is an old Corsair Ax860i
 
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seanmcd said:
I have an EVGA 3080 FTW3 Ultra since new and I use two cables (one being daisy chained) for the three 8 pin plugs. There SHOULD be no issue doing that... My psu is an old Corsair Ax860i
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My naysayer, that it is exact same card I have now
 
I had daisy chained cables power many higher end cards over the last few years, using a Seasonic 1300w psu. Never had a single issue. I think a normal 3080 would be fine.
 
Rev. Night said:
I have a Corsair RMx 750x and I recently bought a 3080 that comes with a triple power connector (3 connectors of 2x8 pin). For all previous cards (including my 7900xtx), they have used a double connector of 2x8pin. I always thought that since the PCIe cable comes with that double head at the end, that only a single pcie cable was needed to power the GPU. I read through google, and saw several articles/message boards saying that this is bad, each connector needs its dedicated pcie cable. Others said I'm fine

If true, wtf do I do with this 2nd header of each pcie cable?
If not true, would 2 cables to power this 3080 be fine? One cable that utilizes both headers, the second cable would only utilize one header
Click to expand...
When I was mining ETH, I used the mani cable and daisy and had no issues. I also watched the power rails via HWinfo. I think the wiring is heavy enough to handle both plugs especially higher qulaity PSUs.
 
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