5 ms·

12vhpwr has almost no safety margin. Any minor problem with it rapidly becomes major. 600W is scary, with reports of 800W spikes. 12V2x6 is particularly proble

12vhpwr has almost no safety margin. Any minor problem with it rapidly becomes major. 600W is scary, with reports of 800W spikes. 12V2x6 is particularly problematic because any imbalance, such as a bad connection of a single pin, will quickly push things over spec. For example, at 600W, 8.3A are carried on each pin in the connector. Molex Micro-Fit 3.0 connectors are typically rated to 8.5A -- That's almost no margin. If a single connection is bad, current per connector goes to 10A and we are over spec. And this if things are mated correctly. 8.5A-10A over a partially mated pin will rapidly heat up to the point of melting solder. Hell, the 16 gauge wire typically used is pushing it for 12V/8.5A/100W -- that's rated to 10A. Really would like to see more safety margin with 14 gauge wire. In short, 12V2x6 has very little safety margin. Treat it with respect if you care for your hardware.

tcdent 2y ago
This is the most informative assessment in this thread. You'd expect to see the capacity to be 125% as is common in other electrical systems. Ratings for connectors and conductors comes with a temperature spec as well, indicating the intended operating temperature at a load. I'm sure, with this spec being near the limit of the components already, that the operating temperatures near full load are not far from the limit, either. Couple that with materials that may not have even met that spec from the manufacturer and this is what you get. Cheaper ABS plastic on the molex instead of Nylon, PVC insulation on the wire instead of silicone, and you just know the amount of metal in the pins is the bare minimum, too.
- zamalek 2y ago
  "3rD party connectors" is being waved around by armchair critics. The connectors on the receiving end of all of this aren't some cheap knock-off, they are from a reputable manufacturer and probably exceed the baseline.
  - Ygg2 2y ago
    No sane individual is going to buy 5090 for $2000-100000 and hook it up to a $15 Power supply.
    - rincebrain 2y ago
      Correct, but it turns out, a fair fraction of the people who day 1 purchase a GPU for that much may not necessarily be described as wholly sane.
      - Ygg2 2y ago
        They aren't insane, just not thrifty with their money.
        rincebrain 2y ago
        They're not necessarily insane, I agree. But I've also known some people who did that when they did not have the disposable income to do it.
        lmm 2y ago
        Doesn't mean they prioritise everything the same way. Plenty of people buy an expensive car and put cheap tires on it or what have you.
        asddubs 2y ago
        Yeah, I can easily see someone buying an expensive GPU but a cheap power supply because they ostensibly all do the same thing
      - m463 2y ago
        your comment makes me wonder... Is it a computer science type person, who might be unaware of electrical engineering... Or someone who takes a perfectly good car and adds ridiculous rims that rub?
    - Decabytes 2y ago
      Let's not forget that the 90 series cards in each generation won't be top end forever. Soon they will just be used cards like all other technology. And someone might be building their first computer, got a good deal on eBay on a 5090 which is 5 or 6 generations old, and cobble it together with some other old parts, and maybe a weak PSU, or an older 12vHP cable
  - tcdent 2y ago
    Show me the Molex logo molded on that connector end and I'll believe you. It's all off-brand slop from companies that learned marketing by emulating western brands. Kids on the internet lap up circuitous threads about one brand being better than the other based on volume. "MODDIY" is a reputable brand? C'mon.
  - clhodapp 2y ago
    The cable must necessarily be third-party from the perspective of the GPU or from the perspective of the power supply. If it's built to the expected tolerance, it should work.
    - Dalewyn 2y ago
      Except when the "expected tolerance" is unreasonable. Even if the connectors and wires are to spec, the design leaves next to no margin for play. You need that margin to account for reality: Handling by casual end-users rather than trained professionals, the ambient temperature of the average room or office, dirt and grime that might get lodged and go unnoticed, wonky supply/draw of power, and more. Running 8.3A through connections rated for 8.5A is "expected tolerance", it's also fucking stupid in no uncertain terms.
      - sozforex 2y ago
        ~23A had been measured going going through one of 6 wires/pins in this test: https://youtu.be/Ndmoi1s0ZaY?t=927 https://youtu.be/Ndmoi1s0ZaY?t=927 Standard requires these connectors to handle 9.5A per pin (9.5 A × 12 V × 6 pin = 684 W). A detailed explanation of this mess: https://www.youtube.com/watch?v=kb5YzMoVQyw https://www.youtube.com/watch?v=kb5YzMoVQyw
        leeter 2y ago
        I'm curious, if there are any high level electrical engineers reading this please respond. I wonder if that vertical (as far as the PCB goes) power connector will always ensure that this sort of imbalance will always occur. While we like to pretend that current is even in any given current plane that's not what happens. The impedance of the wires and copper is not perfectly ideal. This is why these connectors have equal number of grounds, so they have an ideal shortest path and balanced return current path. So I'm curious if electrically it's just impossible to have a vertical connector like that (on that shorts all the pins for 12V together instead of current balancing them) and have it balance current across the pins. The pins closest to the board should in theory have the greatest currents as they are the shortest path electrically. Based on the pictures that appears to be the case. It appears that the pins under the most stress are likely those with the lowest impedance. Assuming my SWAG above is correct... I'm curious if this is affected by the per pin impedance on the PSU too. Where if certain folks are just unlucky get a situation where some pins in the connector have a significantly lower impedance than the rest. If my second SWAG is plausible, my third and really bad SWAG is that removing the two ground pins nearest the PCB could actually "balance" the current better by forcing the current to use a slightly longer path for the power pins. But, my guess is this will just cause EMI issues. So please don't test this unless you're an EE and know what you're doing. This is pure speculation on top of what Buildzoid, the posts above this have said, and what I've learned from Robert Feranec's videos. I'm in no way an electrical engineer, just a humble hobbyist and person that loves to learn.
zamalek 2y ago
> Any imbalance I watched de-Bauer's analysis this morning, and you've seemingly hit the nail on the head. Even on his test bench it looks like only two of the wires are carrying all of the power (instead of all of them, I think 4 would be nominal?) - using a thermal camera as a measuring tool. The melted specimen also has a melted wire. Maybe 24V or 48V should be considered, and higher gauge wires - yes.
- mjevans 2y ago
  It would be _lovely_ if instead of the 12V only spec we went to 48V for internal distribution. Though that would require an ecosystem shift. USB-PD 2.0~3.0 would also be better supported https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver... As others no doubt mention Power (loss, Watts) = I (amsp) * V (volts (delta~change on the wire)). dV = I*R ==> dV = I * I / R -- That is, other things being equal, amps squared is the dominant factor in how much power loss occurs over a cable. In the low voltage realms most insulators are effectively the same and there's very little change in resistance relative to the voltages involved, so it's close enough to ignore. 600W @ 12V? 50A ==> 1200 * R while at 48V ~12.5A ==> 156.25 * R A 48V system would have only ~13% the resistive losses over the cables (more importantly, at the connections!); though offhand I've heard DC to DC converters are more efficient in the range of a 1/10th step-down. I'm unsure if ~1/25th would incur more losses there, nor how well common PC PCB processes handle 48V layers. https://en.wikipedia.org/wiki/Low_voltage#United_States https://en.wikipedia.org/wiki/Low_voltage#United_States """ In electrical power distribution, the US National Electrical Code (NEC), NFPA 70, article 725 (2005), defines low distribution system voltage (LDSV) as up to 49 V. The NFPA standard 79 article 6.4.1.1[4] defines distribution protected extra-low voltage (PELV) as nominal voltage of 30 Vrms or 60 V DC ripple-free for dry locations, and 6 Vrms or 15 V DC in all other cases. Standard NFPA 70E, Article 130, 2021 Edition,[5] omits energized electrical conductors and circuit parts operating at less than 50 V from its safety requirements of work involving electrical hazards when an electrically safe work condition cannot be established. UL standard 508A, article 43 (table 43.1) defines 0 to 20 V peak / 5 A or 20.1 to 42.4 V peak / 100 VA as low-voltage limited energy (LVLE) circuits. """ The UK is similar, and the English Wikipedia article doesn't cite any other country's codes, though the International standard generally talks at the power grid distribution level.
ckozlowski 2y ago
Great summary. Buildzoid over on YouTube came to a similar conclusion back during the 4xxx series issues[1], and looks like he's released a similar video today[2]. It's worth a watch as he gets well into the electrical side of things. It's been interesting to think that we're probably been dealing with poor connections on the older Molex connectors for years, but because of the ample margins, it was never an issue. Now with the high power spec, the underlying issues with the connectors in general are a problem. While use of sense pins sorta helps, I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. That will make connectors more expensive no doubt, but much of the ATX spec and surrounding ecosystem was never designed for "expansion" cards pushing 600-800w. [1] - 12VHPWR failures (2023) https://youtu.be/yvSetyi9vj8?t=1479 https://youtu.be/yvSetyi9vj8?t=1479 [2] - Current issues: https://www.youtube.com/watch?v=kb5YzMoVQyw https://www.youtube.com/watch?v=kb5YzMoVQyw
- exmadscientist 2y ago
  > I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive. Though at 40A+ you tend to see more "banana" type connectors, with a cylindrical piece that has slits cut in it to deform. Those can handle tons of current.
  - ckozlowski 2y ago
    > There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive. That's fair, so maybe not a complete rethink then. But definately a higher standard of quality. Right now, my experience with any of those molex type connectors (be it a 4 pin HDD connector or 8 pin EATX 12V or PCI-e somethingorother) is that they rely on the pin properly aligning with the holder on the other side, and if those aren't lined up, the pin can simply end up pushing the holder and it's wire back, instead of seating correctly. There's plenty of give and play in those cables, and it's hard to tell at a glance if all of them have seated correctly or if a holder has been pushed backwards in it's socket. I can imagine a higher quality connector with tighter tolerances and stiffer materials would lessen the likelihood of this happening, but no doubt with higher costs to PSUs and cards. I suspect manufacturers are sensitive to price increases there, but I have to imagine tacking on even a few dollars to an already exorbitantly priced card that might melt otherwise is a good value? I guess we'll see.
amelius 2y ago
Yes, and by the way I also think typical GPU cables are way too stiff for such a small and fragile connector.
exmadscientist 2y ago
This can't be Micro-Fit 3.0, those are only sized to accept up to 18AWG. At least, with hand crimp tooling, and that's dicey enough that I'd be amazed if Molex allowed anything larger any other way. The hand crimper for 18AWG is separate from the other tools in the series, very expensive, and a little bit quirky. Even 18AWG is pushing it with these terminals. This has to be some other series.
Dalewyn 2y ago
What is the reason the spec keeps specifying next to no headroom? Clearly that was the fundamental problem with 12VHPWR and it's being repeated with 12V2X6. Any engineer worth his salt knows that you should leave plenty of headroom in your designs, you are not supposed to stress your components to (almost) their maximum specifications under nominal use.
- bcrl 2y ago
  I found it hilarious when a friend went to use a Tesla supercharger on his F150 Lightning. As the cable is only long enough to reach the charge port on the corner of a Telsa, he had to block 2 parking spaces and almost 3 chargers to use it. Oops... I hope all the money "saved" on copper was worth it.
snuxoll 2y ago
> Really would like to see more safety margin with 14 gauge wire. The wire itself really isn't the issue, the NEC in the US is notoriously cautious and 15A continuous is allowed on 14AWG conductors. Poor connectors that do not ensure good physical contact is a real problem here, and I really fail to understand the horrid design of the 12VHPWR connector. We went decades with traditional PCIe 2x6 and 2x6 power connectors with relatively few issues, and 12VHPWR does what over them? Save a little bulk?
opello 2y ago
Shouldn't there be a bit better margin if we subtract the 75W from the slot itself? Down to ~7.3A/pin in the 600W example.
Xelbair 2y ago
There were some tests of current draw being imbalanced on each pair. two cables carried 22A - PSU connector heating up near them to 150C rest 2-3A. derbauer has video on that on youtube. 1st party cables too. connector is also a disaster design wise.
caycep 2y ago
RTX 6000 Ada Gen had EPS12V 8 pin or something?
HexPhantom 2y ago
At what point do we stop blaming user error and start admitting the design itself is the problem?
choilive 2y ago
I would bet a lot of money more than 1 engineer at nvda flagged this as a potential issue. If you were going to run this close to the safety margin, I would at minimum add current sensing on each pin.

tcdent 2y ago

This is the most informative assessment in this thread. You'd expect to see the capacity to be 125% as is common in other electrical systems. Ratings for connectors and conductors comes with a temperature spec as well, indicating the intended operating temperature at a load. I'm sure, with this spec being near the limit of the components already, that the operating temperatures near full load are not far from the limit, either. Couple that with materials that may not have even met that spec from the manufacturer and this is what you get. Cheaper ABS plastic on the molex instead of Nylon, PVC insulation on the wire instead of silicone, and you just know the amount of metal in the pins is the bare minimum, too.

zamalek 2y ago
"3rD party connectors" is being waved around by armchair critics. The connectors on the receiving end of all of this aren't some cheap knock-off, they are from a reputable manufacturer and probably exceed the baseline.
- Ygg2 2y ago
  No sane individual is going to buy 5090 for $2000-100000 and hook it up to a $15 Power supply.
  - rincebrain 2y ago
    Correct, but it turns out, a fair fraction of the people who day 1 purchase a GPU for that much may not necessarily be described as wholly sane.
    - Ygg2 2y ago
      They aren't insane, just not thrifty with their money.
      - rincebrain 2y ago
        They're not necessarily insane, I agree. But I've also known some people who did that when they did not have the disposable income to do it.
      - lmm 2y ago
        Doesn't mean they prioritise everything the same way. Plenty of people buy an expensive car and put cheap tires on it or what have you.
        asddubs 2y ago
        Yeah, I can easily see someone buying an expensive GPU but a cheap power supply because they ostensibly all do the same thing
    - m463 2y ago
      your comment makes me wonder... Is it a computer science type person, who might be unaware of electrical engineering... Or someone who takes a perfectly good car and adds ridiculous rims that rub?
  - Decabytes 2y ago
    Let's not forget that the 90 series cards in each generation won't be top end forever. Soon they will just be used cards like all other technology. And someone might be building their first computer, got a good deal on eBay on a 5090 which is 5 or 6 generations old, and cobble it together with some other old parts, and maybe a weak PSU, or an older 12vHP cable
- tcdent 2y ago
  Show me the Molex logo molded on that connector end and I'll believe you. It's all off-brand slop from companies that learned marketing by emulating western brands. Kids on the internet lap up circuitous threads about one brand being better than the other based on volume. "MODDIY" is a reputable brand? C'mon.
- clhodapp 2y ago
  The cable must necessarily be third-party from the perspective of the GPU or from the perspective of the power supply. If it's built to the expected tolerance, it should work.
  - Dalewyn 2y ago
    Except when the "expected tolerance" is unreasonable. Even if the connectors and wires are to spec, the design leaves next to no margin for play. You need that margin to account for reality: Handling by casual end-users rather than trained professionals, the ambient temperature of the average room or office, dirt and grime that might get lodged and go unnoticed, wonky supply/draw of power, and more. Running 8.3A through connections rated for 8.5A is "expected tolerance", it's also fucking stupid in no uncertain terms.
    - sozforex 2y ago
      ~23A had been measured going going through one of 6 wires/pins in this test: https://youtu.be/Ndmoi1s0ZaY?t=927 https://youtu.be/Ndmoi1s0ZaY?t=927 Standard requires these connectors to handle 9.5A per pin (9.5 A × 12 V × 6 pin = 684 W). A detailed explanation of this mess: https://www.youtube.com/watch?v=kb5YzMoVQyw https://www.youtube.com/watch?v=kb5YzMoVQyw
      - leeter 2y ago
        I'm curious, if there are any high level electrical engineers reading this please respond. I wonder if that vertical (as far as the PCB goes) power connector will always ensure that this sort of imbalance will always occur. While we like to pretend that current is even in any given current plane that's not what happens. The impedance of the wires and copper is not perfectly ideal. This is why these connectors have equal number of grounds, so they have an ideal shortest path and balanced return current path. So I'm curious if electrically it's just impossible to have a vertical connector like that (on that shorts all the pins for 12V together instead of current balancing them) and have it balance current across the pins. The pins closest to the board should in theory have the greatest currents as they are the shortest path electrically. Based on the pictures that appears to be the case. It appears that the pins under the most stress are likely those with the lowest impedance. Assuming my SWAG above is correct... I'm curious if this is affected by the per pin impedance on the PSU too. Where if certain folks are just unlucky get a situation where some pins in the connector have a significantly lower impedance than the rest. If my second SWAG is plausible, my third and really bad SWAG is that removing the two ground pins nearest the PCB could actually "balance" the current better by forcing the current to use a slightly longer path for the power pins. But, my guess is this will just cause EMI issues. So please don't test this unless you're an EE and know what you're doing. This is pure speculation on top of what Buildzoid, the posts above this have said, and what I've learned from Robert Feranec's videos. I'm in no way an electrical engineer, just a humble hobbyist and person that loves to learn.

zamalek 2y ago

> Any imbalance I watched de-Bauer's analysis this morning, and you've seemingly hit the nail on the head. Even on his test bench it looks like only two of the wires are carrying all of the power (instead of all of them, I think 4 would be nominal?) - using a thermal camera as a measuring tool. The melted specimen also has a melted wire. Maybe 24V or 48V should be considered, and higher gauge wires - yes.

mjevans 2y ago
It would be _lovely_ if instead of the 12V only spec we went to 48V for internal distribution. Though that would require an ecosystem shift. USB-PD 2.0~3.0 would also be better supported https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver... As others no doubt mention Power (loss, Watts) = I (amsp) * V (volts (delta~change on the wire)). dV = I*R ==> dV = I * I / R -- That is, other things being equal, amps squared is the dominant factor in how much power loss occurs over a cable. In the low voltage realms most insulators are effectively the same and there's very little change in resistance relative to the voltages involved, so it's close enough to ignore. 600W @ 12V? 50A ==> 1200 * R while at 48V ~12.5A ==> 156.25 * R A 48V system would have only ~13% the resistive losses over the cables (more importantly, at the connections!); though offhand I've heard DC to DC converters are more efficient in the range of a 1/10th step-down. I'm unsure if ~1/25th would incur more losses there, nor how well common PC PCB processes handle 48V layers. https://en.wikipedia.org/wiki/Low_voltage#United_States https://en.wikipedia.org/wiki/Low_voltage#United_States """ In electrical power distribution, the US National Electrical Code (NEC), NFPA 70, article 725 (2005), defines low distribution system voltage (LDSV) as up to 49 V. The NFPA standard 79 article 6.4.1.1[4] defines distribution protected extra-low voltage (PELV) as nominal voltage of 30 Vrms or 60 V DC ripple-free for dry locations, and 6 Vrms or 15 V DC in all other cases. Standard NFPA 70E, Article 130, 2021 Edition,[5] omits energized electrical conductors and circuit parts operating at less than 50 V from its safety requirements of work involving electrical hazards when an electrically safe work condition cannot be established. UL standard 508A, article 43 (table 43.1) defines 0 to 20 V peak / 5 A or 20.1 to 42.4 V peak / 100 VA as low-voltage limited energy (LVLE) circuits. """ The UK is similar, and the English Wikipedia article doesn't cite any other country's codes, though the International standard generally talks at the power grid distribution level.

ckozlowski 2y ago

Great summary. Buildzoid over on YouTube came to a similar conclusion back during the 4xxx series issues[1], and looks like he's released a similar video today[2]. It's worth a watch as he gets well into the electrical side of things. It's been interesting to think that we're probably been dealing with poor connections on the older Molex connectors for years, but because of the ample margins, it was never an issue. Now with the high power spec, the underlying issues with the connectors in general are a problem. While use of sense pins sorta helps, I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. That will make connectors more expensive no doubt, but much of the ATX spec and surrounding ecosystem was never designed for "expansion" cards pushing 600-800w. [1] - 12VHPWR failures (2023) https://youtu.be/yvSetyi9vj8?t=1479 https://youtu.be/yvSetyi9vj8?t=1479 [2] - Current issues: https://www.youtube.com/watch?v=kb5YzMoVQyw https://www.youtube.com/watch?v=kb5YzMoVQyw

exmadscientist 2y ago
> I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive. Though at 40A+ you tend to see more "banana" type connectors, with a cylindrical piece that has slits cut in it to deform. Those can handle tons of current.
- ckozlowski 2y ago
  > There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive. That's fair, so maybe not a complete rethink then. But definately a higher standard of quality. Right now, my experience with any of those molex type connectors (be it a 4 pin HDD connector or 8 pin EATX 12V or PCI-e somethingorother) is that they rely on the pin properly aligning with the holder on the other side, and if those aren't lined up, the pin can simply end up pushing the holder and it's wire back, instead of seating correctly. There's plenty of give and play in those cables, and it's hard to tell at a glance if all of them have seated correctly or if a holder has been pushed backwards in it's socket. I can imagine a higher quality connector with tighter tolerances and stiffer materials would lessen the likelihood of this happening, but no doubt with higher costs to PSUs and cards. I suspect manufacturers are sensitive to price increases there, but I have to imagine tacking on even a few dollars to an already exorbitantly priced card that might melt otherwise is a good value? I guess we'll see.

amelius 2y ago

Yes, and by the way I also think typical GPU cables are way too stiff for such a small and fragile connector.

exmadscientist 2y ago

This can't be Micro-Fit 3.0, those are only sized to accept up to 18AWG. At least, with hand crimp tooling, and that's dicey enough that I'd be amazed if Molex allowed anything larger any other way. The hand crimper for 18AWG is separate from the other tools in the series, very expensive, and a little bit quirky. Even 18AWG is pushing it with these terminals. This has to be some other series.

Dalewyn 2y ago

What is the reason the spec keeps specifying next to no headroom? Clearly that was the fundamental problem with 12VHPWR and it's being repeated with 12V2X6. Any engineer worth his salt knows that you should leave plenty of headroom in your designs, you are not supposed to stress your components to (almost) their maximum specifications under nominal use.

bcrl 2y ago
I found it hilarious when a friend went to use a Tesla supercharger on his F150 Lightning. As the cable is only long enough to reach the charge port on the corner of a Telsa, he had to block 2 parking spaces and almost 3 chargers to use it. Oops... I hope all the money "saved" on copper was worth it.

snuxoll 2y ago

> Really would like to see more safety margin with 14 gauge wire. The wire itself really isn't the issue, the NEC in the US is notoriously cautious and 15A continuous is allowed on 14AWG conductors. Poor connectors that do not ensure good physical contact is a real problem here, and I really fail to understand the horrid design of the 12VHPWR connector. We went decades with traditional PCIe 2x6 and 2x6 power connectors with relatively few issues, and 12VHPWR does what over them? Save a little bulk?

opello 2y ago

Shouldn't there be a bit better margin if we subtract the 75W from the slot itself? Down to ~7.3A/pin in the 600W example.

Xelbair 2y ago

There were some tests of current draw being imbalanced on each pair. two cables carried 22A - PSU connector heating up near them to 150C rest 2-3A. derbauer has video on that on youtube. 1st party cables too. connector is also a disaster design wise.

caycep 2y ago

RTX 6000 Ada Gen had EPS12V 8 pin or something?

HexPhantom 2y ago

At what point do we stop blaming user error and start admitting the design itself is the problem?

choilive 2y ago

I would bet a lot of money more than 1 engineer at nvda flagged this as a potential issue. If you were going to run this close to the safety margin, I would at minimum add current sensing on each pin.