Is it safe to pull constant 320w from a daisy chain 8-pin PCI-E cable?

[Vasllo]

So, I've got a TX550M (2015/2016 model) that only has 1 PCI-E cable and just got a used RTX 3080 for a good price, it seems it's capable of powering it, but pulling 320w and spikes of 450~500w out of a single PCI-E cable has got me a bit worried rn. I know it's not ideal, but is it dangerous?

[Shimejii]

Dont put decent hardware on  cheap shit PSU's. Its just not worth it.

 

It can be dangerous, if you overload the wires they can easily fry and catch fire. Probably wont, but it isnt unheard of.

[Hinjima]

3 minutes ago, Shimejii said:

Dont put decent hardware on  cheap shit PSU's. Its just not worth it.

 

It can be dangerous, if you overload the wires they can easily fry and catch fire. Probably wont, but it isnt unheard of.

The TXM series from Corsair is actually not a bad PSU lineup at all.  It even has 7 year warranty.  This could be the later models however and not the 2015/2016 model that OP has.

That being said, I would not power a 3080 with a 550w PSU with one daisychain cable.

[LeapFrogMasterRace]

You can calculate if it is technically safe (probably is) but in the end if it sounds bad just don't do it is my take. As a side note you generally want a bit of headroom anyway to keep the PSU in its most efficient zone. 

[Vasllo]

1 minute ago, Shimejii said:

Dont put decent hardware on  cheap shit PSU's. Its just not worth it.

 

It can be dangerous, if you overload the wires they can easily fry and catch fire. Probably wont, but it isnt unheard of.

A Corsair TX 550M 80 Plus Gold is a cheap shit PSU? The hell you on about? This is the most generic answer possible.

 

Any ways, I searched its review on Cybenetics and checked the PCI-E cables are 18AWG and found 18AWG wires can handle up to 8A, which at 12V equals to 96W, given there are 3 12V wires in a 8-pin PCI-E cable, it sums up to 284W limit. Having said that, I'm unsure if Corsair has more 12V wires in their cable.

 

2 minutes ago, Hinjima said:

The TXM series from Corsair is actually not a bad PSU lineup at all.  It even has 7 year warranty.  This could be the later models however and not the 2015/2016 model that OP has.

That being said, I would not power a 3080 with a 550w PSU with one daisychain cable.

The old model has a pretty good review on Cybenetics indeed. But yeah, I'm thinking I would be pushing it, by my own math. And if I undervolt/power limit, I could lose enough performance to make it not worth it.

 

Well, now I'm gonna weigh in my options, which are:

1 - Give up on the upgrade;

2 - Buy a new PSU and spend even more money that I really shouldn't;

3 - Spend the price of the 3080 + PSU on a brand new 4070, which seems the best option, but might be too expensive for rn.

[Vasllo]

2 minutes ago, LeapFrogMasterRace said:

You can calculate if it is technically safe (probably is) but in the end if it sounds bad just don't do it is my take. As a side note you generally want a bit of headroom anyway to keep the PSU in its most efficient zone. 

Agreed. But the PSU power isn't the issue, I'm worried about the PCI-E 8-pin daisy chain cable. I saw a video of a similar build power-wise and it was pulling just 500w from the wall with a lower efficiency PSU, so I would at most reach 80% load, but the cable might be over the limit. I guess I'll ask Corsair.

[Hinjima]

6 minutes ago, Vasllo said:

A Corsair TX 550M 80 Plus Gold is a cheap shit PSU? The hell you on about? This is the most generic answer possible.

 

Any ways, I searched its review on Cybenetics and checked the PCI-E cables are 18AWG and found 18AWG wires can handle up to 8A, which at 12V equals to 96W, given there are 3 12V wires in a 8-pin PCI-E cable, it sums up to 284W limit. Having said that, I'm unsure if Corsair has more 12V wires in their cable.

 

The old model has a pretty good review on Cybenetics indeed. But yeah, I'm thinking I would be pushing it, by my own math. And if I undervolt/power limit, I could lose enough performance to make it not worth it.

 

Well, now I'm gonna weigh in my options, which are:

1 - Give up on the upgrade;

2 - Buy a new PSU and spend even more money that I really shouldn't;

3 - Spend the price of the 3080 + PSU on a brand new 4070, which seems the best option, but might be too expensive for rn.

A RTX 4070 only draws 200w at max load so its definitely a lot more efficient than a 3080 in terms of power consumption.

You can safely run the 4070 on the TX550M without any worries.

 

What is your budget for a new PSU if you were to buy one?

[seon123]

There is no TX550M 2015 or 2016 model. There is an ancient one from 2011 with a yellow label, one from 2017 with gray label and wire grill, and one from 2021 with a black label and triangles on the grill. If it's the 2017 or 2021 models, it might have 16 AWG wires to the first connector and HCS terminals (you would need to verify that, Cybenetics indicates 18 AWG on the 2017 model, but that may be incorrect), which would be fine, since the 3080 also pulls power from the PCIe slot, and those high end cables are fine for 300W on their own. The 3080 has a 350W TDP, so the entire system should pull about 450W under a gaming load. If it doesn't shut down, and you've verified that it uses the higher end cables, it's fine. If the cable uses 18 AWG wires and regular MiniFit Jr terminals, you could also get newer Type 4 cables from Corsair, which should be 16 AWG to the first connector, and HCS terminals, for $4.

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920143/type-4-sleeved-black-pcie-cable-with-pigtail-connector-and-capacitors-for-type-4-psu-cp-8920143

 

 

Some companies still cheap out on their cables by using just 18 AWG wires and regular MiniFit Jr terminals, even on their highest end PSUs, which is why you might see recommendations to not use the daisy chained connector on PCIe cables. Seasonic is infamous for this.

Edited May 23 by seon123
Something something

[Shimejii]

12 minutes ago, Vasllo said:

A Corsair TX 550M 80 Plus Gold is a cheap shit PSU? The hell you on about? This is the most generic answer possible.

 

 

550W PSUS are generally not all that great, no matter the 80 Plus Gold sticker.  For a Basic system without much power demands, yeah its fine. For a 3080? Yes its a Cheap shit PSU. Its a Basic 550 PSU, thats all it was really meant for. 3080 is well beyond the scope of what it was designed for.

 

Go with hardware that it was actually designed for, ends up doing you better in the long run

[Alex Atkin UK]

28 minutes ago, Shimejii said:

550W PSUS are generally not all that great, no matter the 80 Plus Gold sticker.  For a Basic system without much power demands, yeah its fine. For a 3080? Yes its a Cheap shit PSU. Its a Basic 550 PSU, thats all it was really meant for. 3080 is well beyond the scope of what it was designed for.

 

Go with hardware that it was actually designed for, ends up doing you better in the long run

I think the point is moot anyway, its recommended to have an 850W for a 3080 due its absurd power spike issue.

 

I tried mine on a Coolermaster 650W and it would randomly shut down, it did work on an RM650X, but a TX550M I kind doubt it.

 

Strangly Corsair even recommend not using both 8 pin connectors off the same cable which is kinda odd considering they are okay with using them with the 12HWPR adapter and their own 12HPWR cable only has two sets of cables at the other end.

[Vasllo]

31 minutes ago, Hinjima said:

A RTX 4070 only draws 200w at max load so its definitely a lot more efficient than a 3080 in terms of power consumption.

You can safely run the 4070 on the TX550M without any worries.

 

What is your budget for a new PSU if you were to buy one?

Yeah, it pulls the same as my RTX 3060 Ti, it would be fine, but I really didn't want to spend more. Currency aside, I can sell mine for 1.5k, I got the 3080 for 2.5k and a 4070 goes for 3.3k at the very best, so I had to add 1k for the 3080, but would have to add 1.8k for the 4070. I might run it downclocked/undervolted until Black Friday and get a new PSU, I already wanted to get a RM750e for a while, pass my TX550M to my sister and use her CX450 for diagnosis on PCs I build or fix.

 

28 minutes ago, seon123 said:

There is no TX550M 2015 or 2016 model. There is an ancient one from 2011 with a yellow label, one from 2017 with gray label and wire grill, and one from 2021 with a black label and triangles on the grill. If it's the 2017 or 2021 models, it might have 16 AWG wires to the first connector and HCS terminals (you would need to verify that, Cybenetics indicates 18 AWG on the 2017 model, but that may be incorrect), which would be fine, since the 3080 also pulls power from the PCIe slot, and those high end cables are fine for 300W on their own. The 3080 has a 350W TDP, so the entire system should pull about 450W under a gaming load. If it doesn't shut down, and you've verified that it uses the higher end cables, it's fine. If the cable uses 18 AWG wires and regular MiniFit Jr terminals, you could also get newer Type 4 cables from Corsair, which should be 16 AWG to the first connector, and HCS terminals, for $4.

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920143/type-4-sleeved-black-pcie-cable-with-pigtail-connector-and-capacitors-for-type-4-psu-cp-8920143

 

 

Some companies still cheap out on their cables by using just 18 AWG wires and regular MiniFit Jr terminals, even on their highest end PSUs, which is why you might see recommendations to not use the daisy chained connector on PCIe cables. Seasonic is infamous for this.

True, it's a 2017 model, I didn't recall when I posted it. And holy shit, how did I forget about the PCI-E slot power?! That changes everything. And the 3080 has a 320w TDP, 350w is the 3080 Ti. About the cable, it seems like a really good deal, but I'm in South America, so I'm not even sure I can get those, I'll contact local Corsair Support, they've helped me a lot even outside warranty. Thanks a whole lot for all that info!

 

24 minutes ago, Shimejii said:

550W PSUS are generally not all that great, no matter the 80 Plus Gold sticker.  For a Basic system without much power demands, yeah its fine. For a 3080? Yes its a Cheap shit PSU. Its a Basic 550 PSU, thats all it was really meant for. 3080 is well beyond the scope of what it was designed for.

 

Go with hardware that it was actually designed for, ends up doing you better in the long run

Yeah, you just sound like ChatGPT, thanks, but not helpful at all.

 

7 minutes ago, Alex Atkin UK said:

I think the point is moot anyway, its recommended to have an 850W for a 3080 due its absurd power spike issue.

 

I tried mine on a Coolermaster 650W and it would randomly shut down, it did work on an RM650X, but a TX550M I kind doubt it.

Yeah, that's also what I was afraid of. I think I'll just downclock and undervolt it until my PSU handles it until I upgrade the PSU. Your insight was helpful, thanks.

[Alex Atkin UK]

1 minute ago, Vasllo said:

Yeah, that's also what I was afraid of. I think I'll just downclock and undervolt it until my PSU handles it until I upgrade the PSU. Your insight was helpful, thanks.

Not sure that will help as the problem is it will spike to 2-3x its rated TDP.  The cable would be fine for such short bursts, but the PSUs overload protection will likely kick in.

[Vasllo]

7 minutes ago, Alex Atkin UK said:

Not sure that will help as the problem is it will spike to 2-3x its rated TDP.  The cable would be fine for such short bursts, but the PSUs overload protection will likely kick in.

Will it power spike to the same ranges even after limiting it's power usage? Holy, I'm screwed. A friend of mine managed to run a GTX 1080 Ti on a CX450 by slightly limiting it.

[Alex Atkin UK]

25 minutes ago, Vasllo said:

Will it power spike to the same ranges even after limiting it's power usage? Holy, I'm screwed. A friend of mine managed to run a GTX 1080 Ti on a CX450 by slightly limiting it.

No idea, but given it goes so far past the limit I'd suspect it might.  Maybe if you limit the clock rate that might work better.

[seon123]

1 hour ago, Alex Atkin UK said:

Strangly Corsair even recommend not using both 8 pin connectors off the same cable which is kinda odd considering they are okay with using them with the 12HWPR adapter and their own 12HPWR cable only has two sets of cables at the other end.

The maximum current rating for dual row 8 pin wire-to-board connections from the Molex specifications for Mini-Fit Plus HCS lists 10A with 16 AWG wires.

Spoiler

On a PCIe cable with 3 12V wires, that's 30A, or 360W. 

 

It's more than fine, and Corsair definitely knows it, since as you mentioned, their 12VHPWR cable correctly uses only two connectors on the PSU side. 

Edited May 23 by seon123
Something something

[Alex Atkin UK]

2 hours ago, seon123 said:

The maximum current rating for dual row 8 pin wire-to-board connections from the Molex specifications for Mini-Fit Plus HCS lists 10A with 16 AWG wires.

  Reveal hidden contents

On a PCIe cable with 3 12V wires, that's 30A, or 360W. 

 

It's more than fine, and Corsair definitely knows it, since as you mentioned, their 12VHPWR cable correctly uses only two connectors on the PSU side. 

Sure, but you also need the wire to be the appropriate AWG for that, but it sounds like not necessarily.

 

I assume their modular PSUs are, given they use the same cables across the whole range.  So this seems to be a quirk of the cheaper hardwired models, or at least under 650W ones?

[seon123]

9 hours ago, Alex Atkin UK said:

Sure, but you also need the wire to be the appropriate AWG for that, but it sounds like not necessarily.

 

I assume their modular PSUs are, given they use the same cables across the whole range.  So this seems to be a quirk of the cheaper hardwired models, or at least under 650W ones?

Any non modular cables wouldn't use these connectors on the PSU end, so that should just take away the issue of cheaping out on the connectors. And the wires should be at least 18 AWG, which should be fine. On the PCIe side each connector should only pull 150W anyway, so the terminals there don't matter as much. 

[Alex Atkin UK]

11 hours ago, seon123 said:

Any non modular cables wouldn't use these connectors on the PSU end, so that should just take away the issue of cheaping out on the connectors. And the wires should be at least 18 AWG, which should be fine. On the PCIe side each connector should only pull 150W anyway, so the terminals there don't matter as much. 

Yeah but Corsair themselves say:

Quote

A single 8-pin connector’s maximum current rating is up to, and sometimes more than 24A (288W at 12V).

You'd think they would be screaming from the rooftops that THEIR cables can handle 300W, rather than being so vague and then saying:

Quote

 it is not recommended to use a single cable that splits into two 8-pin PCIe on graphics cards that utilize two PCIe connectors to consume over 288W

This just comes across as covering their ass so if a cable melts they can claim its not their fault.  When it IS their fault as if the cable or PSU connector can't handle 300W, it shouldn't have two 150W plugs on it.

 

Although I do blame GPU manufacturers too, they seem to wire all the pins together on the GPU when they should have a current limited on each 12V pin so it literally CAN'T go over the limit for a prelonged period, but allow the brief bursts.  Its just stupid to assume the load is going to be evenly spread across all pins.

[seon123]

2 hours ago, Alex Atkin UK said:

Yeah but Corsair themselves say:

You'd think they would be screaming from the rooftops that THEIR cables can handle 300W, rather than being so vague and then saying:

This just comes across as covering their ass so if a cable melts they can claim its not their fault.  When it IS their fault as if the cable or PSU connector can't handle 300W, it shouldn't have two 150W plugs on it.

 

Although I do blame GPU manufacturers too, they seem to wire all the pins together on the GPU when they should have a current limited on each 12V pin so it literally CAN'T go over the limit for a prelonged period, but allow the brief bursts.  Its just stupid to assume the load is going to be evenly spread across all pins.

They claim it's fine up to 288W through the PCIe connectors, which is close enough to 300W to really matter. With 75W from the PCIe slot, that's claiming 363W graphics cards are fine, but 375W cards are not. So that would be fine for OP, and the difference would matter for barely any cards, if it matters at all. 

 

Compare this to Seasonic, which recommends separate cables for graphics cards above 225W. Not 225W through the PCIe cables, as one might be mislead to believe, but 225W in total, so 150W through the PCIe cables. Cutting corners on the cables, and then using misleading language to tell their customers, quite disappointing from them, but not surprising. 

https://knowledge.seasonic.com/article/8-installation-remark-for-high-power-consumption-graphics-cards

[Vasllo]

So, my 3080 arrived in less than 24h, so here are my first tests:

- 3DMark TimeSpy Extreme;

- Furmark;

- Furmark + Prime95;

- Furmark (GPU +9% power limit) + Prime95;

- Destiny 2 in 4k;

- Cyberpunk 2077 in 4k;

 

Not once my PC shut down. The last Furmark test took my PC to the limit, there was just too much heat (30ºC ambient) and my CPU got to 97ºC, GPU to 88ºC, PCI-E cable was nearly too hot to hold and the PSU was, for the first time, exhausting actually hot air. Pulled 590~600w from the wall. Since it took this torture test well, I plan on keeping the 3080 to around 300w max (-30w) and my CPU under normal usage pulls 40w less than in Prime95.

 

The 3080 is a Phoenix model and is running rather hot, but it's used (3 years) and hasn't been opened, so I'll clean it up and change paste after I'm sure it's working fine for a little longer. Also gonna clean the whole PC and change my CPU's paste as well.

[Alex Atkin UK]

49 minutes ago, seon123 said:

They claim it's fine up to 288W through the PCIe connectors, which is close enough to 300W to really matter. With 75W from the PCIe slot, that's claiming 363W graphics cards are fine, but 375W cards are not. So that would be fine for OP, and the difference would matter for barely any cards, if it matters at all.

I don't think slot power is that simple.  My 4070 Ti pulls only 24W from the 12V rail via the slot and the 4090 FE only 10W.  Not sure what the other HwInfo fields mean so its likely drawing power for other voltage rails on the slot too, for example GPU FBVDD Input Power says 37W, GPU Input PP Source Power (sum) says 47W.

 

I'm not sure if that 75W is specifically the 12V rail or includes the other voltages on the slot.  I think GPUs specifically on their TDP are referring to the 12V rail so the slot may provide a lot less than 75W on the 12V rail specifically.

 

This is further suggested given % TDP in HwInfo64 seems to be calculated based on the 12V rail consumption.