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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

#111

Post by ta988 »

mpreda wrote: post #103
ta988 wrote: post #99

Earlier quoted context omitted.

But you would then need to bring it down to the low voltages required by the chips and that would greatly increased cost, volume, weight, electrical noise and heat of the device.

The voltage step-down is already in place, from 12V to whatever 1V or 0.8V is needed. Doing the same thing starting from 48V instead of 12V does not change anything fundamentally, I guess.

It changes a lot. You are switching at different frequencies and although the currents are smaller, there is an increased cost if you want to do it efficiently and not have too many losses.

But anyway for consumer products this is unlikely to happen because it would force users to get new power supplies which would reduce their sales quite drastically at least for the first one they make like that.

The solution would maybe be to make a low volume 48V card and slowly move people over it showing them it is better?

Anyway this is clearly not a case of "just use X" where X is 48V. It is much more subtle than that.

Re: Nvidia's RTX 5090 power connectors are melting

#112

Post by Kirby64 »

ielillo wrote: post #108
Kirby64 wrote: post #101

Earlier quoted context omitted.

Until the US changes their AC power connectors, we just don’t have a use case for it frankly. When the entire system is going to always top out at 1200W or so (so you have an extra few hundred watts for monitors and such), we’re pretty limited to maximum amperage.

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.

I’m aware we have 240V outlets. They are just not used in a place where you would put a PC. Until there is a shift in need (I.e., every normal user would need more than a 120V plug could handle), you won’t ever see 240V outlets in offices. I suspect it will never happen.

In server areas and extremely specialized stuff? Yea, sure. But we’re talking desktop PCs here.

Re: Nvidia's RTX 5090 power connectors are melting

#113

Post by revnode »

ielillo wrote: post #108
Kirby64 wrote: post #101

Earlier quoted context omitted.

Until the US changes their AC power connectors, we just don’t have a use case for it frankly. When the entire system is going to always top out at 1200W or so (so you have an extra few hundred watts for monitors and such), we’re pretty limited to maximum amperage.

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.

Re: Nvidia's RTX 5090 power connectors are melting

#114

Post by michaelt »

ta988 wrote: post #99
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…

But you would then need to bring it down to the low voltages required by the chips and that would greatly increased cost, volume, weight, electrical noise and heat of the device.

Nah, modern GPUs are already absolutely packed with buck converters, to convert 12v down to 2v or so.

Look at the PCB of a 4090 GPU; you can find plenty of images of people removing the heatsink to fit water blocks. They literally have 24 separate transistors and inductors, all with thermal pads so they can be cooled by the heatsink.

The industry could change to 48v if they wanted to - although with ATX3.0 and the 16-pin 12VHPWR cable being so recent, I'd be surprised if they wanted to.

Re: Nvidia's RTX 5090 power connectors are melting

#115

Post by gloxkiqcza »

dragontamer wrote: post #82
Havoc wrote: post #77

What’s wild is that this is a company clearly capable of designing highly complex things with numerous tradeoffs, challenges and unknowns. And then the fuckin cable is the issue. Repeatedly.

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

Re: Nvidia's RTX 5090 power connectors are melting

#116

Post by unshavedyak »

Workaccount2 wrote: post #104
BigJono wrote: post #13

This shit is so fucking dumb. Sorry for the unhinged rant, but it's ridiculous how bad every single connector involved with building a PC is in 2025. I'm just a software guy, so maybe some hardware engineer can chime in (and I'd love to find out exactly what I'm missing and why it might be harder than it seems), but why on earth can everything not just be easily accessible and click nicely into place? I'm paying mult…

I work in power electronics and there are ample connectors that can handle any type of power requirement. What is happening in the computer space is that everyone is clinging to an old style of doing things, likely because it is free and open, and suggestions to move to new connectors get saddled with proprietary licensing fees. D-sub power connectors have been around forever (they even look like the '90s still) and…

Man would i prefer screw in. I hate snap. All of those things in motherboards that require serious force and if you don't know what you're doing it's quite easy to not realize the reason something isn't going in is because of a block/issue, rather than not enough force. So the user adds more force and bam, something breaks.

Then of course there's just so much force in general it's easy for a finger/hand to slip and bump/hurt something else, etcetc.

I tend not to enjoy PC building because of that. Screws on everything would be so nice imo. Doubly so if we could increase the damn motherboard size to support these insane GPU sizes lol.

Re: Nvidia's RTX 5090 power connectors are melting

#117

Post by mpreda »

Kirby64 wrote: post #101
mpreda wrote: post #100

Step the GPU voltage up to 48V. (anyway you make a new connector that's not compatible with existing PSUs. Why not actually fix a problem at the same time, once and for all! [48V should be enough for anybody, right?])

Until the US changes their AC power connectors, we just don’t have a use case for it frankly. When the entire system is going to always top out at 1200W or so (so you have an extra few hundred watts for monitors and such), we’re pretty limited to maximum amperage.

Now I must use lots of rather thick cables in my desktop (because I run GPUs).

Imagine that the GPU would instead suck up all the power it needs through the PCIe connector, without all those pesky cables. (right now PCIe can provied 75W at 12V, i.e. 6.25A; that same current would provide 300W at 48V).

Re: Nvidia's RTX 5090 power connectors are melting

#118

Post by jeffbee »

ta988 wrote: post #111
mpreda wrote: post #103

Earlier quoted context omitted.

The voltage step-down is already in place, from 12V to whatever 1V or 0.8V is needed. Doing the same thing starting from 48V instead of 12V does not change anything fundamentally, I guess.

It changes a lot. You are switching at different frequencies and although the currents are smaller, there is an increased cost if you want to do it efficiently and not have too many losses. But anyway for consumer products this is unlikely to happen because it would force users to get new power supplies which would reduce their sales quite drastically at least for the first one they make like that. The solution would…

> a low volume 48V card

I wouldn't be shocked if someone told me that Nvidia already sells more 48V parts than consumer 12V parts.

Re: Nvidia's RTX 5090 power connectors are melting

#119

Post by KeplerBoy »

DannyBee wrote: post #97
Havoc wrote: post #77

What’s wild is that this is a company clearly capable of designing highly complex things with numerous tradeoffs, challenges and unknowns. And then the fuckin cable is the issue. Repeatedly.

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.
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