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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

#451

Post by rcxdude »

KeplerBoy wrote: post #271
fooker wrote: post #247

Earlier quoted context omitted.

Have you measured latency? In modern(last 4 years approximately) GPUs, physical wiring distance is starting to contribute substantially to latency.

latency due to wiring distances is far from being an issue in these scenarios. The signals travel at the speed of light. 186 miles per millisecond. The problem you will encounter with pcie gen5 risers is signal integrity.

A single round trip isn't going to register, but there are multiple in a frame, so it's not inconceivable that it could add up at some point. I would like to see it demonstrated, though.

Re: Nvidia's RTX 5090 power connectors are melting

#452

Post by lazide »

snuxoll wrote: post #391
flyingpenguin wrote: post #149

Earlier quoted context omitted.

The problem there would be your breaker. I am not an electrition but I can tell you that when I tried adding a heated MAU to my house, I had to switch to a 120v washer/dryer because my electric panel did not have space for another 208v line. (Note, my building is actually 3 phase 208 volt not 240volt so I don't have 240 volt plugs but 208volt plugs)

Not a criticism, but a question. Did you consider adding a subpanel? If you're running a new circuit I assume there was already some drywall patching to be done, seems like it would have been more cost effective and removed future headaches to just give yourself more breaker space.

At least in the US, a sub panel is an easy grand or two even if it’s right next to the main panel.

Re: Nvidia's RTX 5090 power connectors are melting

#453

Post by leeter »

exmadscientist wrote: post #433
leeter wrote: post #419

Earlier quoted context omitted.

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 eq…

Paralleling wires is stable because the TCR of copper is positive. When one connection carries too much current compared to its peers, it will heat up. This will increase its resistance, causing it to accordingly carry less of the current. So the system is self-balancing. Do not remove ground wires. That is stupid. You'll just be raising the current in the remaining wires. EMI should not be a major concern as we are…

Yeah I realized that was the worst way to go about testing that anyway right after I went to bed last night. If (big stress on if) that was the issue a ferrite bead would be a better way to test it. Based on what you're saying my SWAGs were wildly off. I'd still like to see the sims of it however to see if they provide any illumination on the issue. What makes me think something weird is going on is that it's two out of six wires heating up to absurd degrees. Of the other four two are carrying normal currents and the last two (based on Roman's video) are carrying practically nothing. Buildzoid makes the convincing argument that clearly Nvidia engineers were aware of something like this could happen on the 3090. But, then didn't carry that over to the 4090/5090.

Re: Nvidia's RTX 5090 power connectors are melting

#455

Post by Schiendelman »

deelowe wrote: post #366
Schiendelman wrote: post #50

Earlier quoted context omitted.

Then the graphics card would have to have a transformer on it to step down to the voltage that the chips can handle.

No one uses transformers anymore. VRRs are basically mini PCs now. They run firmware and report telemetry and are crazy efficient.

I'm not familiar with this! I've tried to investigate but I just get variable refresh rate. Tell me more?

Re: Nvidia's RTX 5090 power connectors are melting

#456

Post by numpad0 »

NoPicklez wrote: post #411
wnevets wrote: post #202

Why are people using 3rd party cables after the 40 series disaster?

Because often it is the case that third party cables are of higher quality than stock cables, if you purchase from reputable vendors

Gamer judgement on "quality" is often misplaced and skewed towards cosmetic novelty though...

Re: Nvidia's RTX 5090 power connectors are melting

#457

Post by asddubs »

lmm wrote: post #373
Ygg2 wrote: post #328

Earlier quoted context omitted.

They aren't insane, just not thrifty with their money.

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.

Yeah, I can easily see someone buying an expensive GPU but a cheap power supply because they ostensibly all do the same thing

Re: Nvidia's RTX 5090 power connectors are melting

#458

Post by johnwalkr »

Neikius wrote: post #244
johnwalkr wrote: post #234

Earlier quoted context omitted.

A higher input voltage may eventually be used but a standard PC power supply only has 12V and lower (5V and 3.3V) available, so they'd need to use a new type of power supply or an external power supply, both of which are tough sells. On the other hand, the voltages used inside a GPU are around 1V, and a higher input voltage introduces lower efficiency in the local conversion. 12V is only really used because historica…

Lower voltage would be OK, but then all of the cables and plugs would need to be redesigned. And there would still need to be for voltage switching unless we start adding a protocol and have PSU switch voltage dynamically... which is also not efficient. Since they went so far to create a new cable which wont be available on old PSU they would have easily extended that slightly and introduced an entirely new PSU class…

There are versions of the cables (and adapters) that work on older PSUs, although new PSUs are starting to come with the same connector that new GPUs have.

Anyway there are pros and cons to using 12V, or lower or higher, and anything except 12V would require a new PSU so it's a hard sell. But even without that detail, I have a feeling 12V is a reasonable choice anyway, not too low or high for conversion either in the PSU or in the GPU or other component.

In any case, at the end of the day sending 12V from the PSU to GPU is easy. The connector used here is bad, either by design or manufacturing quality, but surely the solution can be a better housing and/or sockets on the cable side connectors instead of a different voltage.

Re: Nvidia's RTX 5090 power connectors are melting

#459

Post by johnwalkr »

formerly_proven wrote: post #15
lyu07282 wrote: post #4

It's strange how Nvidia just doubled down on a flawed design for no apparent reason. It doesn't even do anything, the adapter is so short you still have the same mess of cables in the front of the case as before.

This connector somehow has it's own Wikipedia page and most of it is about how bad it is. Look at the table at the end: https://en.wikipedia.org/wiki/16-pin_12VHPWR_connector#Relia... The typical way to use these is also inherently flawed. On the nVidia FE cards, they use a vertical connector which has a bus bar connecting all pins directly in the connector. Meanwhile, the adapter has a similar bus bar where all the…

Was the old design actively balanced? I think the current of each pin was only monitored.

Re: Nvidia's RTX 5090 power connectors are melting

#460

Post by shawnz »

ssl-3 wrote: post #434
cameronh90 wrote: post #430

Earlier quoted context omitted.

If GPUs requiring 2kW PSUs do become reality, at least us Europeans would have something new to flaunt over the US, along with our fast boil electric kettles.

Here in the States, I've already banished non-Metric "Freedom units" from my workshop. I can do the same with 120v. (And indeed: Back in the mining days, my somewhat diminutive rig was running from a dedicated 240v circuit. It made my already-efficient power supplies a tiny bit more efficient, and it saved a bit on copper. I've already got plans for 240v outlets in the kitchen.)

> I've already got plans for 240v outlets in the kitchen.

Likewise, I just need to find a kettle with a NEMA 6-15 plug

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