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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

#331

Post by makeitdouble »

Miraste wrote: post #300
michaelt wrote: post #144

Earlier quoted context omitted.

The USB-C connectors on laptops and phones can deliver 240 watts [1] in a 8.4x2.7mm connector. 12VHPWR is 8.4x20.8mm so it's got 7.7x the cross-sectional area but transmits only 2.5x the power. And 12VHPWR also has the substantial advantage that GPUs have fans and airflow aplenty. So I can see why someone looking at the product might have thought the connector could reasonably be shrunk. Of course, the trick USB-C us…

The spec may say it, but I've never encountered a USB-C cable that claims to support 240 watts. I suspect if machines that tried to draw 240W over USB-C were widespread, we would see a lot of melted cables and fires. There are enough of them already with lower power draw charging.

240W cables are here but at around a 10x price premium. Also cables are chipped so e.g. a 100W cable won't allow 240 in the first place.

Users needing the 240W have a whole chain of specialized devices, so buying a premium cable is also not much of an issue.

Re: Nvidia's RTX 5090 power connectors are melting

#332

Post by dragontamer »

immibis wrote: post #276
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 card that draws 600 watts likely already has more than 6 phases of power conversion, so it could put a separate phase on each pin, and one more on the PCIe slot power, and then guarantee load balancing as well as being able to detect any single broken connection.

Could do yes.

But when Founders Edition cards made by NVidia are $2000 and the FE editions have no such mechanism, why would any AIB maker go above and beyond?

You just make your cards more expensive and it's difficult to tell consumers what the difference is exactly.

Re: Nvidia's RTX 5090 power connectors are melting

#333

Post by quickthrowman »

superjan wrote: post #266
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…

When you work with normal AC power, it is considered unsafe practice to use parallel wires to share load in a circuit. Reason: one might get decoupled somehow, you don’t notice, and when fully loaded the heat causes a fire risk. This problem sounds similar. A single fat wire is the easiest, but I guess it’s not that simple.

> When you work with normal AC power, it is considered unsafe practice to use parallel wires to share load in a circuit.

The NEC permits using conductors #1/0AWG or larger for parallel runs, it doesn’t forbid it entirely.

Re: Nvidia's RTX 5090 power connectors are melting

#334

Post by makeitdouble »

DebtDeflation wrote: post #312
Miraste wrote: post #300

Earlier quoted context omitted.

The spec may say it, but I've never encountered a USB-C cable that claims to support 240 watts. I suspect if machines that tried to draw 240W over USB-C were widespread, we would see a lot of melted cables and fires. There are enough of them already with lower power draw charging.

Search Amazon for "240W USB" and you get multiple pages of results for cables. A few years ago there was a recall of OnePlus cables that were melting and catching fire, I had 2 of them and both melted. But yes 240W/48V/5A is insane for a spec that was originally designed for 0.5W/5V/100mA. I suspect this is the limit for USB charging as anything over 48V is considered a shock hazard by UL and 5A is already at the ver…

We've had a variety of 140W laptops for a few years already, so the original spec has been far away for a while now.

The advantage of USB-C is the power negotiation, so getting the higher rating only on circuits that actually support it should de doable and relatively safe.

The OnePlus cable melting give me the same impression as when hair power cables melt: it's a solved problem, the onus is on the maker.

Re: Nvidia's RTX 5090 power connectors are melting

#335

Post by fredoliveira »

xxpor wrote: post #299
rollcat wrote: post #242

Earlier quoted context omitted.

Can we talk about how absolutely terrifying is that 600W figure? We're not transcoding or generating slop as the primary use case, we're playing computer games . What was wrong with the previous-generation graphics that we still need to push for more raw performance, rather than reducing power draw?

Why should we reduce power draw? We live in an age of abundance.

Can you point me to the abundance? Because I sure can point you to the consequences of thinking we live in an age of abundance.

Re: Nvidia's RTX 5090 power connectors are melting

#336

Post by jgalt212 »

UberMouse wrote: post #317
jgalt212 wrote: post #288

Earlier quoted context omitted.

Too true. I've been looking replace my 1080. This was a beast in 2016, but the only way I can get a more performant card these days is to double the power draw. That's not really progress.

Then get a modern GPU and limit the power to what your 1080 draws. It will still be significantly faster. GPU power is out of control these days, if you knock 10% off the power budget you generally only lose a few percentage of performance. Cutting the 5090 down from 575w to 400w is a 10% perf decrease.

Even if I knew how to do that, I'd still need double the power connectors I currently have.

Re: Nvidia's RTX 5090 power connectors are melting

#337

Post by myself248 »

mjevans wrote: post #305
zamalek wrote: post #290

Earlier quoted context omitted.

> 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.

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.

Re: Nvidia's RTX 5090 power connectors are melting

#338

Post by malfist »

colejohnson66 wrote: post #232
anankaie wrote: post #188

Earlier quoted context omitted.

I did not realize the outlet impacts the amperage… Is it a rating issue, or is there an actual part there that will trip?

The outlet itself doesn't care, but the shape of the receptacle is supposed to restrict insertion of a 20 amp device into a 15 amp socket. You can stick a 15 amp device into a 20 amp socket, but not vice versa. The electrician should be installing 20 amp sockets if the cabling can support it, but many don't. It's the difference between NEMA 5-15 and 5-20: https://en.wikipedia.org/wiki/NEMA_connector#NEMA_5

NEMA 5-20 is only required for commercial. You can use NEMA 5-15 on a 20A circuit for residential in the US.

Re: Nvidia's RTX 5090 power connectors are melting

#339

Post by malfist »

ryao wrote: post #297
Kirby64 wrote: post #241

Earlier quoted context omitted.

We do, but they’re limited to much lower wattage due to the outlet limits. A typical US kettle is 1100-1400W, and takes maybe 1-2 minutes to boil. Kettles in the UK are typically 2.5-3kW.

Amazon lists 1500W models: https://www.amazon.com/electric-kettles/b

And they're probably not real. Take look at any of the clones of the dyson hair dryer and check their proclaimed RPMs, many of them would have the tip of the fan blade spinning at several mach if they actually hit their limit.

There's aquarium heaters on amazon that say they're 10kw or more and plug into a 120 outlet.

I bought a magnet that is supposed to hold "150 pounds", but pulls off the ceiling (in it's strongest position) with just 10-15 pounds.

Amazon specs are fake.

Re: Nvidia's RTX 5090 power connectors are melting

#340

Post by mastax »

marcyb5st wrote: post #259

I hope that a brand that produce PSUs and GPUs develop a higher voltage rail and a card that goes with it as an open standard. Wishful thinking, I know. Especially because I don't even know if they can drift from the nVidia/AMD specs that much before being sanctioned or something. Yeah, they will be more expensive, but I'd rather pay few bucks more and be safer/not to worry to burn my house down.

IIRC at the last PC trade show (the one in Taipei) one of the GPU+Motherboard makers was showing a prototype system where the PCIe slot had an additional slot behind it just for power, so no cables were required. Of course then that additional power needs to get into (and flow across) the motherboard somehow.
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