[SOLVED] Pigtail PCI-E power connectors ?

[avg9956]

Recently came across this video today (luckily I did):

View: https://www.youtube.com/watch?v=D2Ahkv-64rs

And it advises to avoid using both connectors from a Pigtail style PCI-E connector if your GPU is rated above 225W (i.e. if you have a 2x 6+2 pin connectors, you should only use one of them. You then have to use an additional, separate PCI-E power connector to power for every other slot on your GPU).

This can easily be the RTX 3070 - RTX 3090 GPUs which have >225W power draw
Or AMD's RX 6700XT - RX 6900XT
And highly probably, Nvidia's next gen RTX 40 series GPUs (which are rumored to be even more power hungry than the RTX 30 series)

However this advice is coming specifically from Seasonic only, saying that it applies to all of their PSUs. I have Seasonic PSUs so I will heed this advice.

I wondering though if this applies generally to all other PSUs? Googling "PCI-E Pigtail avoid" seems that the issue is not yet made aware yet or hasn't been an issue at all.
Not unless PSU manufacturers make a new line of PSUs next year that gives us thicker gauged PCI-E power connectors to handle more current/wattage, some people can run into this issue where their PCI-E pigtail connectors could burst into flames.

 

[siaan312]

It's not as good as using 2 cables, that's for sure, but it's probably fine.
A card like an rtx 3090 might take more than 225watts, but remember, you can't use a just 1 pigtail. a 3090 has 3, 6+2 connectors, spreading the load.
any card with only 2 connectors can be connected with just a single pigtail on any decent modern powersupply with no worry.

 

[Math Geek]

exactly. this pops up every few months but is not really a problem with a quality unit.

anything is possible with the junk units sold cheaply all over the world though. on a quality unit, i'd not be concerned at all with using the full pig tail.

if it was really a problem, we'd see non-stop posts and lots of media coverage. a random youtube video every few months is not even close to showing a true problem. i assure you if there was a true problem, every tech site on the web would have it covered and tested non-stop.

 

[velocityg4]

A single 8 pin PCIe power connector is rated for 150w. The PCIe slot is rated for 75W. That's where they get the 225W number.

The problem is those dual connectors imply the cable is rated for 300W. This is a failure of the PSU manufacturer. There should be a warning listing max draw and fuses in the lines if the cable can't supply the rated current of both connectors. Better yet they should just use a heavier gauge cable which can handle the current of both connectors.

I don't know where the guy making that Youtube video gets the idea that high TDP cards are new. This is an old and outdated excuse. They may have been caught flat footed when the Radeon HD 4870 x2 or GTX 480 came out. But they've had over ten years to adjust to the fact that there are GPU with a TDP of over 225W. They should have updated their wiring decisions accordingly.

Now a good quality unit normally uses a much heavier gauge wire than the spec calls for. If the 8pin wiring harness uses 16AWG wire and is 50 cm long. It should easily handle 300w. The problem is cheap PSU may use 18AWG or even 20AWG. Which won't handle the load.

Poor cable quality isn't solely in the domain of this connector. There's cheap SATA connector using mold injection which can't handle their 54W rating. Junk replacement power cables which are using aluminum or even steel wire. It goes on and on. So, buy trusted brands from trustworthy sources for anything electrical.

 

[Bazzy 505]

pigtails are perfectly fine, if the wire gague is sized correctly and secondary side to which it is attached on PSU is equally equipped to handle the load. If your see zem evil cables included with the better brands like corsair, you really have nothing to worry about.

 

[jonnyguru]

Recently came across this video today (luckily I did):

View: https://www.youtube.com/watch?v=D2Ahkv-64rs

And it advises to avoid using both connectors from a Pigtail style PCI-E connector if your GPU is rated above 225W (i.e. if you have a 2x 6+2 pin connectors, you should only use one of them. You then have to use an additional, separate PCI-E power connector to power for every other slot on your GPU).

This can easily be the RTX 3070 - RTX 3090 GPUs which have >225W power draw
Or AMD's RX 6700XT - RX 6900XT
And highly probably, Nvidia's next gen RTX 40 series GPUs (which are rumored to be even more power hungry than the RTX 30 series)

However this advice is coming specifically from Seasonic only, saying that it applies to all of their PSUs. I have Seasonic PSUs so I will heed this advice.

I wondering though if this applies generally to all other PSUs? Googling "PCI-E Pigtail avoid" seems that the issue is not yet made aware yet or hasn't been an issue at all.
Not unless PSU manufacturers make a new line of PSUs next year that gives us thicker gauged PCI-E power connectors to handle more current/wattage, some people can run into this issue where their PCI-E pigtail connectors could burst into flames.

Depends on the PSU amd the use case. The melted cable in Tech YES City's video was used by a miner.

I can't speak for Seasonic, but the Corsair PSUs are 16g to the first connector, then 18g to the second. If the factory uses 18g across the board, then I can see that being a bad idea.

 

[avg9956]

I think 18g is the common wire gauge of PSU power connectors. I've come across them enough fairly often when looking at after market cables online.
I measured the cables of my seasonic PSU and they have the same thickness as 18g. No doubt I'll avoid pigtails just to be on the safe side.

 

[jonnyguru]

I think 18g is the common wire gauge of PSU power connectors. I've come across them enough fairly often when looking at after market cables online.
I measured the cables of my seasonic PSU and they have the same thickness as 18g. No doubt I'll avoid pigtails just to be on the safe side.

That's too bad.

18g is not "the common wire gauge". It's common for brands like Seasonic. Like I said, Corsair PCIe cables are 16g. That applies to even the cheaper stuff like CX and CV.

Another problem with some PSUs like Seasonic is the terminals. This is more important than the wire gauge itself. They should use HCS (high current system) terminals which are rated at 13A max. Instead, they're using the cheaper standard mini-fit terminals which only support 9A and isn't even supposed to support 16g wire.

In the video, the miner that fried the cable on the Corsair HX was definitely putting a heavy, sustained load on the PSU to melt that connector. If you're not mining, and actually using the PC for what it's intended for, this would not happen.

If other companies cheap out by using 18g, that's really a shame. But copper is expensive. Any way to shave cost where average customers won't "notice".

Housing: WST P6-I42002K19 (BLACK) or approved equivalent (LST/HYM/YIYI) and WST P2-I42002K13A (BLACK) or approved equivalent (LST/HYM/YIYI).

Terminal: Molex HCS (44476-1111) or approved equivalent (HCS Plus/WST HC/LST/HYM/YIYI/YY).

All wire must be black in color, UL 1007, VW-1 rated, hardness 55P or approved equivalent.

​

Pin​	AWG​	Signal​	Color​	Pin​	AWG​	Signal​	Color​
1​	16AWG​	+12VDC​	Black​	5​	16AWG​	COM​	Black​
2​	16AWG​	+12VDC​	Black​	6​	16AWG​	COM​	Black​
3​	16AWG​	+12VDC​	Black​	7​	16AWG​	COM​	Black​
4​	16AWG​	COM​	Black​	8​	16AWG​	COM​	Black​

​

 

[--SID--]

Another problem with some PSUs like Seasonic is the terminals. This is more important than the wire gauge itself. They should use HCS (high current system) terminals which are rated at 13A max. Instead, they're using the cheaper standard mini-fit terminals which only support 9A and isn't even supposed to support 16g wire.

Aha, that's why they recommond to use 2 seperate cables for a >225w GPU?

 

[jonnyguru]

Aha, that's why they recommond to use 2 seperate cables for a >225w GPU?

Yes.

 

[Barcod]

That's too bad.

18g is not "the common wire gauge". It's common for brands like Seasonic. Like I said, Corsair PCIe cables are 16g. That applies to even the cheaper stuff like CX and CV.

Another problem with some PSUs like Seasonic is the terminals. This is more important than the wire gauge itself. They should use HCS (high current system) terminals which are rated at 13A max. Instead, they're using the cheaper standard mini-fit terminals which only support 9A and isn't even supposed to support 16g wire.

In the video, the miner that fried the cable on the Corsair HX was definitely putting a heavy, sustained load on the PSU to melt that connector. If you're not mining, and actually using the PC for what it's intended for, this would not happen.

If other companies cheap out by using 18g, that's really a shame. But copper is expensive. Any way to shave cost where average customers won't "notice".

​

But Aris' review claims to indicate that PCIE cables are 18AWG for units below RMx (2018) except for RMx (2021)...

 

[Bazzy 505]

But Aris' review seems to indicate that PCIE cables are 18AWG for units below RMx (2018) except for RMx (2021)...

That's not entirely accurate have 2 RM750i units, one purchased in 2015 the other in 2017. PCIEx cables both units came packed with are AWG16 from PSU to first 8 pin to first connector than split from first connector to second with AWG18 wires.

 

[jonnyguru]

But Aris' review claims to indicate that PCIE cables are 18AWG for units below RMx (2018) except for RMx (2021)...

Then he's wrong.

Even CX-M has 16g to the first connector, then 18g to the second (because you can't put two 16g wires in an HCS terminal).

 

[Barcod]

Then he's wrong.

Even CX-M has 16g to the first connector, then 18g to the second (because you can't put two 16g wires in an HCS terminal).

If you're right, can't you ask Aris to revise the review? Also, IIRC, the RMx has the WT7502 and WT7518, but Aris' review only mentions the WT7502, and some seem to think there is no OCP.