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Nvidia's RTX 5090 power connectors are melting

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Re: Nvidia's RTX 5090 power connectors are melting

#401

Post by sozforex »

Dalewyn wrote: post #389
clhodapp wrote: post #345

Earlier quoted context omitted.

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.

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 thr…

~23A had been measured going going through one of 6 wires/pins in this test: 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

Re: Nvidia's RTX 5090 power connectors are melting

#402

Post by nullifidian »

armada651 wrote: post #239
nullifidian wrote: post #230

Earlier quoted context omitted.

>Because no PC power supply has a 24V rail Servers with NVIDIA H200 GPUs (Supermicro ones for example) have power supplies that have 54 volt rail, since that gpu requires it. I can easily imagine a premium ATX (non-mandatory, optional) variant that has higher voltage rail for people with powerful GPUs. Additional cost shouldn't be an issue considering top level GPUs that would need such rail cost absurd money nowaday…

A server is not a personal computer. We are talking about enthusiast GPUs here who will install these components into their existing setup whereas servers are usually sold as a unit including the power supply. > Additional cost shouldn't be an issue considering top level GPUs that would need such rail cost absurd money nowadays. Bold of you to assume that Nvidia would be willing to cut into its margin to provide an o…

>Nvidia would be willing to cut into its margin to provide

Why would that be optional on a top of the line GPU that requires it? NVIDIA has nothing to do with it. I'm talking about defining an extended ATX standard, that covers PSUs, and it would be optional in the product lines of PSU manufacturers. The 12VHPWR connector support in PSUs is already a premium thing, they just didn't go far enough.

Re: Nvidia's RTX 5090 power connectors are melting

#403

Post by shawnz »

MBCook wrote: post #398
shawnz wrote: post #364

Earlier quoted context omitted.

What's the proposal here, just convince everyone to stop demanding more powerful hardware?

Stop and try again? Either you’re not going to get a choice, or you’ll need a 240v three phase outlet installed and possibly an expanded electrical panel. Nvidia has been all about “as fast as possible, no compromise” for a very long time now. So was Intel, until the Pentium 4 forced a big reset. At a certain point this stuff is just totally untenable. Throw more amps at it stops being workable. Apple seems to be abl…

Plenty of people are working hard to tackle the performance-per-watt problem while others simultaneously tackle the absolute performance problem. There's no one single metric you can focus exclusively on that's going to satisfy everyone's use cases. Obviously not everyone needs a high-end enthusiast product like the 5090 and plenty of people are going to be seeking out a middle-of-the-road product that focuses on performance-per-watt instead, which will be accommodated by the lower-tier products in the lineup as well as their competitors' products.

> Given how parallel graphics problems are, maybe it’s time to give up on 100 cores that go uber fast as behave like a space heater and move to 250 cores that go quite fast but use 1/4 of the power each.

It wasn't too long ago that people were saying the same things about single-core and dual-core NetBurst CPUs and how we need to start considering dual-core and quad-core for consumer CPUs. And now we have consumer CPUs with 64 cores and more, so aren't we moving in the direction you want already? Performance-per-watt is improving, parallelism is improving, and also absolute performance is improving too in addition to those other metrics.

Re: Nvidia's RTX 5090 power connectors are melting

#404

Post by aaronmdjones »

elorant wrote: post #105

All these incidents are from aftermarket cables.

All 12V-2x6 GPU power cables are aftermarket third-party cables. Nvidia doesn't make or supply one because PSUs have different pinouts (or may not be modular in design at all). This isn't any different to the previous situation of PCIe 8-pin power connectors on GPUs that don't come with 8-pin cables.

They do ship an adapter for older PSUs.

All of those cables and the adapter are all using the same 12VHPWR connector as standardised by PCI-SIG, with the same gauge wire. I find it highly unlikely that any of them are more safe than any other.

We really need to get out of the mindset of blaming non-first-party stuff unless one can actually demonstrate an issue with a specific product, such as CableMod's (rightly) recalled right-angle adapter (which wasn't a cable, by the way).

At the end of the day this connector has a 10% margin of safety, while a PCIe 8-pin connector had a 92% margin of safety. It is incredibly delicate, much more prone to failure, and will result in a much more spectacular failure when it does fail.

It boggles my mind that it hasn't been written off and replaced yet.

Re: Nvidia's RTX 5090 power connectors are melting

#405

Post by boznz »

myself248 wrote: post #337
mjevans wrote: post #305

Earlier quoted context omitted.

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_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…

I've been beating the 48v drum for years. Any inefficiency in the 48-to-1 conversion should be mostly offset by higher efficiency in the 240-or-120-to-48 conversion, I suspect it's a wash. Every PoE device handles 48 without issue on normal PCB processes, so I don't expect that to be a big deal either. They _also_ have a big gap for galvanic isolation but that wouldn't be necessary here.

POE/POE+ standard is 15-20W. 600W would mean another standard

Re: Nvidia's RTX 5090 power connectors are melting

#406

Post by opello »

kersplody wrote: post #273

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…

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.

Re: Nvidia's RTX 5090 power connectors are melting

#407

Post by Panzer04 »

leeter wrote: post #128
enragedcacti wrote: post #87

Earlier quoted context omitted.

Summary of the Buildzoid video courtesy of redditors in r/hardware: > TL;DW: The 3090 had 3 shunt resistors set up in a way which distributed the power load evenly among the 6 power-bearing conductors. That's why there were no reports of melted 3090s. The 4090/5090 modified the engineering for whatever reason, perhaps to save on manufacturing costs, and the shunt resistors no longer distribute the power load. Therefo…

Honestly with 50A of current we should be using connectors that screw into place firmly and have a single wipe or a single solid conductor pin style. Multi-pin connectors will always inherently have issues with imbalance of power delivery. With extremely slim engineering margins this is basically asking for disaster. I stand by what I've said elsewhere: If I was an insurance company I'd issue a notice that fires caus…

I was wondering if this was a thing - in RC quads and the like we use these massive bullet connectors (XT30/60/90 and similar) which often have lower resistances than the wires themselves.

Yeah, they take soldering for the wire/connector interface, but presumably there are connectors similarly designed with crimp terminals, or it's just something the mfgs will have to deal with.

Re: Nvidia's RTX 5090 power connectors are melting

#408

Post by Joel_Mckay »

kllrnohj wrote: post #378
Joel_Mckay wrote: post #367

Earlier quoted context omitted.

In general, poorly designed cables will use steel instead of tin plated copper conductors. The differences become more relevant at higher power levels, as energy losses within the connectors will be higher. Thus, the temperatures rise above the poorly specified unbranded plastic insulator limits, and a melted mess eventually trips the power supply to turn off. I would assume a company like NVIDIA wouldn't make a powe…

derbauer did an analysis of the melted connector. It was nickel & gold, not steel. buildzodes analysis showed Nvidia removed all ability to load balance the wires which they used to have with the 30xx connector that introduced it, and they had even fancier solutions for the multi 8/6 pin connectors before that. The specification also has an incredibly low safety factor, much much lower than anything that came before.…

Nickel & gold plating is common, but if it were solid (rare because that would be expensive and stupid)... you would be looking at 3 to >5 times worse performance than the same sized plated copper plug with a beryllium copper leaf spring.

Have a gloriously wonderful day... I could be wrong, but it has been awhile =3

Re: Nvidia's RTX 5090 power connectors are melting

#409

Post by bigstrat2003 »

wnevets wrote: post #222
dylan604 wrote: post #208

Earlier quoted context omitted.

they're cheaper?

That sounds like someone buying a Lamborghini then trying to save money by fueling with regular gas.

But with gas the difference is at least somewhat legible to the layman. You see the octane rating and know you're getting something for that extra money. With cables they all look the same to the uninitiated, after all it connects doesn't it? So people are going to go for the cheaper option because they can't discern a reason not to.

Re: Nvidia's RTX 5090 power connectors are melting

#410

Post by clhodapp »

Dalewyn wrote: post #389
clhodapp wrote: post #345

Earlier quoted context omitted.

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.

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 thr…

There are at least two issues here:

1) The designed safety margin is unacceptably low. It should be set such that any cable that complies with the expected safety tolerance for carrying current is safe to use.

2) The late-model Nvidia cards in particular have no feedback system to discover unbalanced current on 12v wires that make up the connector and no circuitry to keep the current balanced even if they did. That is, they forgo any digital control and depend on the physical properties of the conductors to be perfectly balanced.

Overall, Nvidia failed to learn from the melting connector issues in the RTX 4000 series and doubled down by increasing the power draw while further cost-cutting the safety circuitry.

See:

    * High-level demonstration: https://youtu.be/Ndmoi1s0ZaY?si=bkv12pXG4K5T72YN
  
    * Low-level explanation: https://youtu.be/kb5YzMoVQyw?si=Bl5aowND4uXoI8s6
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