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RTX 5090 FE Molten 12VHPWR

kalston said:
I'm a little confused. PCI-E 8 pins is 150w, so when pushing 900w they were out of spec for all wires? (nearly 300w per wire assuming perfect balancing?!)

Did the 8pin connectors have that much margin or did they maybe use a CPU power connector instead? Those EPS ones are rated much higher (over 300w) and I suppose they could be modded to work on a GPU.

edit: on their Youtube channel I see custom connectors, not PCIE 8pin connectors. Still neat, don't get me wrong. But seems like some things got lost in translation maybe.
Click to expand...
It looks like a lot more margin on the PCI-E 8 pin connectors. The test is what temperature they are when under load. 35C sounds really good as the concern here is mostly resistive heating as I don't think 35C is high enough to affect metal platings. Keeping it to 25C is even more better.
 
it’s going under the knife right now!!!

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kalston said:
I'm a little confused. PCI-E 8 pins is 150w, so when pushing 900w they were out of spec for all wires? (nearly 300w per wire assuming perfect balancing?!)

Did the 8pin connectors have that much margin or did they maybe use a CPU power connector instead? Those EPS ones are rated much higher (over 300w) and I suppose they could be modded to work on a GPU.

edit: on their Youtube channel I see custom connectors, not PCIE 8pin connectors. Still neat, don't get me wrong. But seems like some things got lost in translation maybe.
Click to expand...

The PCI-E 8 pins were designed to carry over 300W each but were limited to 150W. They were designed that way for safety and so you could daisy chain 2 connectors on the same card.
 
Starfalcon said:
The PCI-E 8 pins were designed to carry over 300W each but were limited to 150W. They were designed that way for safety and so you could daisy chain 2 connectors on the same card.
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Yep it had a very nice safety factor you could cut a wire and the others would still not burn....the new one if you run full power it will degrade and burn
 
TXE36 said:
While the mechanics of this failure is simple, the cause is likely complex. The bottom line is this connector and/or implementation doesn't work and may be unsafe. This problem cannot be fixed by hanging some do-dad on the power connector.

The mechanics is too much resistance in the connections at the pin and likely also the wire crimps for the amount of current the pin is passing. In fact, that's the only thing that can be happening that is melting the wire insulation and plastic connector housings. It is extremely difficult to protect against this because it is likely the amount of current is in spec for the video card. Things like fuses and circuit breakers are designed for fault conditions - this isn't a fault condition. If the video card broke up the phases properly, it likely could detect the voltage drop of a overly restive pin and shut down the card. However, splitting the phases costs more money and provides fewer leather jackets. (The more I'm thinking about this, the real cause does appear to be lack of power phases on the 4090 and 5090s, see below).

The cause is a whole other kettle of fish. Based on reports of connections lasting a long time and then smoking, I'm suspicious of the wires themselves and the plating on the connector sockets and pins. This plating is designed to maintain low resistance over a specified number of mating cycles and atmospheric exposure. I hope they are using copper wires and not some garbage like copper coated aluminum. It could also be simple overload of the per pin current rating (see below). It can also be combinations of all of these sorts of things, hence complex.

A common way to enshitify a connector is to go cheap on that plating. Another way is making the mechanical tolerances more sloppy. The causes I'm mentioning here are speculation, but I'm sure the connector manufacturer knows what is going on and there have been uncomfortable meetings about this.

IMHO, Nvidia has a very big problem here with a connector that now has a large installed base. I can see a big recall in their future and heaven help them if this manages to burn a house down.

I watched the first few minutes of the Buildzoid video which was inspired by a der8auer video and it does look like the fault here is Nvidia is using the connector wrong and not balancing the load. der8auer's IR video clearly shows only two wires/pins are providing the bulk of the power to the 5090 -- this is really, really poor engineering:

View attachment 825240

I skimmed the Buildzoid video and he is right on target. Remember on previous Nvidia cards like the 1080TI, if you forgot to plug in a power connector, the card would not go into 3D mode. The card could sense this because of the split power phases in the voltage regulator.

Providing 600W of power at 12V requires 50A of current, so one has to spread this out over several wires. The problem is, the current magnitude is high enough here that it gets sensitive to the resistance of each wired connection and prefers the ones with lower resistances, this can over load them and cause their resistance to increase, making the problem worse. Split power phases forces the current to split rather than relying on the resistances of each connection to be the same.

Going to a 24V feed instead of 12 would help too as only 25A would be required at 24V for a 600W load. This kind of change has been done before - the development of the ATX12 connector for the CPU. This was done because feeding the CPU regulator with 5V was burning up motherboard ATX power connectors. ATX12 was easy as it's just another connector. 24V is tricky because the voltage rail itself is new.

Multi-kilobuck video cards designed with power connector/feeds like this is a really sad state of affairs. Enshittification is everywhere these days.
Click to expand...

"Maybe Buildzoid ALSO knows nothing about how computers work!".

- Nvidia apologists, probably
 
AVATARAT said:
Be careful when adding a second connector to the Gigabyte 5090, especially if you plan to use it with a power consumption above 600 W:

View attachment 826279

Source
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As an experienced engineer without any other data to go by, feeding all those MOSFETs from that one tiny connector on the upper right just looks wrong.

Not commenting on the circled crater, just using the picture because it is convenient. However, that blowed up real good!
 
If it's the card I'm thinking about je was trying to push 1kw though it of course something on the vrm is going to pop
 
The video is old; you can watch it here, as I linked to it in my previous post.

I know people who actually use this mod with a second connector—generally speaking, this is risky, but it distributes the power between the two connectors, which makes it harder for them to melt.

It’s only possible on the Gigabyte model because there are already wired paths on the board, and the 12VHPWR port is simply soldered to it.
 
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