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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

#131

Post by wing-_-nuts »

gloxkiqcza wrote: post #115
dragontamer wrote: post #82

Earlier quoted context omitted.

Both of my previous cars had door recalls. Ford Focus Mk3 and Prius Prime 2024. Yup. The door had weird failure cases that needed a recall. -------- Connectors and cables is damn near Masters level in knowledge and application. Its a rarely studied and often ignored piece of engineering. The more you learn about them, the crazier it gets. That being said, this news that the 4090 and 5090 are using but one shunt resis…

A bit off topic, but this is something HN might enjoy. It’s a video by a mechanical engineer that worked for Tesla, Apple and a NASCAR team about Tesla door handles over time. https://youtu.be/Bea4FS-zDzc

I see content like this, and it inspires me for what I want my retirement to be like. Just some crazy old eccentric puttering about, tinkering in his workshop. I want my back yard to look like a solar punk world's fair.

Re: Nvidia's RTX 5090 power connectors are melting

#132

Post by c2h5oh »

enragedcacti wrote: post #87
ulfbert_inc wrote: post #71

Derbauer and Buildzoid on YouTube made nice informative videos on subject, and no it is not "simply a user error". So glad I went with 7900 XTX - should be all set for a couple of years.

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…

- Most 12VHPWR connectors are rated to 9.5-10A per pin. 600W / 12V / 6 pin pairs = 8.33A. Spec requires 10% safety factor - 9.17A.

- 12VHPWR connectors are compatible with 18ga or at best 16ga cables. For 90C rated single core copper wires I've seen max allowed amperages of at most 14A for 18ga and 18A for 16ga. Less in most sources.. Near the connectors those wires are so close they can't be considered single core for purpose of heat dissipation..

Re: Nvidia's RTX 5090 power connectors are melting

#133

Post by Joker_vD »

KeplerBoy wrote: post #119
DannyBee wrote: post #97

Earlier quoted context omitted.

This is because they are trying to parallel like 50amps (it's 12 volt IIRC) over a few conductors to get to 600watts. If it becomes unbalanced due to any number of reasons, none of those individual cables can come close to handling it - they will all generate enough heat to melt lots of things. Conservatively, they'd have to be 8awg each to be able to handle the full load without melting if they ended up taking the f…

If only we had connectors which could actually handle such currents. Maybe something along the lines of an XT90, but no Nvidia somehow wants to save a bit of space or weight on their huge brick of a card. I don't get it.

If only we had electrical and thermal fuses that could be used to protect the connectors and wires.

Re: Nvidia's RTX 5090 power connectors are melting

#134

Post by kllrnohj »

fredoralive wrote: post #28
onli wrote: post #26

Earlier quoted context omitted.

I don't think thats correct. Nvidia used that connector first and then a similar PCI spec came out. Compatibility is limited. See https://www.hwcooling.net/en/nvidia-12pin-and-pcie-5-0-gpu-p... from back then.

I'd forgotten about the weird 30 series case, but the 40/50 series ones are the PCI spec connector.

Being a PCI spec connector doesn't mean it isn't an Nvidia thing. It seems pretty likely at this point that Nvidia forced this through, seeing as there's zero other users of this connector. Convincing PCI spec consortium to rubber stamp it probably wasn't very hard for Nvidia to do.

Re: Nvidia's RTX 5090 power connectors are melting

#135

Post by dcrazy »

revnode wrote: post #113
ielillo wrote: post #108

Earlier quoted context omitted.

The USA has 240 volt plugs. They are only used for high power appliances such as AC or ovens. If you want, you could add a plug for your high powered space heater AKA gaming PC.

We also have 20 amp wiring, 20 amp breakers, 20 amp sockets, and plugs too. A lot easier than going 240 volt. That will give you 2400 watts max.

Most residential wiring is 15A except for bathrooms.

Re: Nvidia's RTX 5090 power connectors are melting

#136

Post by wing-_-nuts »

slightwinder wrote: post #92
ulfbert_inc wrote: post #71

Derbauer and Buildzoid on YouTube made nice informative videos on subject, and no it is not "simply a user error". So glad I went with 7900 XTX - should be all set for a couple of years.

> So glad I went with 7900 XTX - should be all set for a couple of years. Really depends on the use case. For gaming, normal office, smaller AI/ML or video-work, yeah, it's fine. But if you want the RTX 5090 for the VRAM, then the 24GB of the 7900 XTX won't be enough.

Honestly, the smart play in that case is to buy 2 3090's and connect them with nvlink. Or...and hear me out, at this point you could probably just invest your workstation build budget and use the dividends to pay for runpod instances when you actually want to spin up and do things.

I'm sure there are some use cases for 32gb of vram but most of the cutting edge models that people are using day to day on local hardware fit in 12 or even 8gb of vram. It's been a while since I've seen anything bigger than 24gb but less than 70gb.

Re: Nvidia's RTX 5090 power connectors are melting

#137

Post by seanw444 »

Hamuko wrote: post #127
ulfbert_inc wrote: post #71

Derbauer and Buildzoid on YouTube made nice informative videos on subject, and no it is not "simply a user error". So glad I went with 7900 XTX - should be all set for a couple of years.

I had two AMD 7900 XTX and they both overheated like mad. Instant 110°C and throttle. Opted for a refund instead of a third GPU.

Probably reference cards, yeah? I think the common advice is to not buy the reference cards. They rarely cool enough. I made that mistake with the RX 5700 XT, and will never again.
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