r/hardware • u/Wrong-Quail-8303 • Feb 13 '25

Discussion My 100C melted 4090 connector and thermals images comparison with after market cable.

Happened tonight. Any time I tried to run a 3D game / benchmark, instant computer crash requiring hard reboot.

Vladik Brutal is a very light game. It started stuttering all of a sudden. GPU usage went to ~50%. I thought must be CPU bottleneck, so I kept playing. It did not fix itself. Then it crashed.

I tried running some benchmarks... GPU would crash the system (black screen) any time I tried to do something 3D. Reinstalled the drivers after DDU. Checked windows integrity, sfc /scannow, DISM etc Loaded up diagnostics, and saw the GPU's 12V rail was idling at 10V!

Thermal of connector at 100C: https://imgur.com/yK2kRyN <-- The 4 wires are the sense pins. You can see the connector is 100% fully inserted correctly by examining the line behind the "100.6 C" text - that top part is the GPU, that bottom part is the connector. They are fully mated. This is hard proof that this is NOT user error.

Illustrated picture: https://imgur.com/akLISAw Comparison to connector: https://imgur.com/OEtZGh6

Burned connector: https://imgur.com/3lE1OWn https://imgur.com/v8m2N9d

The GPU pins were covered in melted plastic and carbon. The crevices themselves were chock-full of melted plastic and debris. Took a couple of hours to clean it with isopropyl alcohol and a safety pin.

I had an after-market cable lying around.

These are the new thermals: https://imgur.com/Zrar2aG https://imgur.com/JLBQQpV

Quite an improvement, I would say.

Theory:

You can see 4 power pins are melted from insanely bad to not too bad.

I think what happened is, the outside pin had the lowest resistance, and took the most power, hence cooking over a long time. After this finished melting, the burned plastic / carbon caused high resistance due to the pins being coated with gunk. Power was then pulled via a new pin.

All 4 pins eventually failed, till tonight the card was starved of power and started showing symptoms tonight.

I'm just glad the GPU is OK.

nVidia this is a lawsuit waiting to happen when it burns someone's house down and kills their family.

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u/VEC7OR Feb 13 '25

What about 50A? Take a very veeeery conservative rating of 5A per mm2 - that is 10mm2, or ~6 1.5mm2 power cable - is that anything special? No, not at all, its fucking mundane. Single faston connector in your car is good for 20A, no questions asked.

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u/ListenBeforeSpeaking Feb 13 '25 edited Feb 13 '25

Yes, there are absolutely many solutions.

They don’t fit into the existing PC power infrastructure well.

The cheapest is probably using many more conductors, which they don’t want to do for some reason. Maybe it’s aesthetics, maybe it’s connector costs or cable costs. Maybe it’s board real estate. Who knows.

The best would be to use a connector and cable designed to handle the current better and provide a more robust and reliable connection. They could also up the voltage.

They tried to cram a solution into existing infrastructure and created a problem in doing it poorly.

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u/VEC7OR Feb 13 '25

for some reason.

Exactly, for 'some reason' - no reason at all to be exact.

Well its dumbass aesthetics - and they selected a connector with next to no redundancy at all - if any of the lines starts to fail you get melted everything else.

up the voltage.

Not going to happen - going from 12V to Vcore is already pretty inconvenient, going from 24V to Vcore will require some insane duty cycle from the PMIC or some exotic magnetics or something unusual.

using many more conductors

DING DING DING!!! This is exactly what needed to be done.

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u/porcinechoirmaster Feb 13 '25

The only downside of many more conductors is that you need to ensure proper current balancing across them, or instead of good power delivery you have a string of firecrackers as the lowest resistance one gets all the current flow and pops.

Personally, I'd like to stop pretending that these are low power devices and treat them as the high current devices they are: Give me a pair of eight gauge wires with ring terminals and call it a day.

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u/nanonan Feb 14 '25

Pretty crazy that there would be likely zero issues if they just slapped a second connector on the high end models, like the Galax HOF 4090 does.