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Nvidia won, we all lost

(blog.sebin-nyshkim.net)
977 points todsacerdoti | 12 comments | 04 Jul 25 21:58 UTC | HN request time: 1.204s | source | bottom
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rkagerer ◴[05 Jul 25 01:22 UTC] No.44469388[source]▶
I am a volunteer firefighter and hold a degree in electrical engineering. The shenanigans with their shunt resistors, and ensuing melting cables, is in my view criminal. Any engineer worth their salt would recognize pushing 600W through a bunch of small cables with no contingency if some of them have failed is just asking for trouble. These assholes are going to set someone's house on fire.

I hope they get hit with a class action lawsuit and are forced to recall and properly fix these products before anyone dies as a result of their shoddy engineering.

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1. ryao ◴[05 Jul 25 02:39 UTC] No.44469723[source]▶
Has anyone made 12VHPWR cables that replace the 12 little wires with 2 large gauge wires yet? That would prevent the wires from becoming unbalanced, which should preempt the melting connector problem.

As a bonus, if the gauge is large enough, the cable would actually cool the connectors, although that should not be necessary since the failure appears to be caused by overloaded wires dumping heat into the connector as they overheat.

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2. bobmcnamara ◴[05 Jul 25 02:44 UTC] No.44469751[source]▶
Or 12 strands in a single sheath so it's not overly rigid.
3. alright2565 ◴[05 Jul 25 02:47 UTC] No.44469763[source]▶
Might help a little bit, by heatsinking the contacts better, but the problem is the contact resistance, not the wire resistance. The connector itself dangerously heats up.

Or at least I think so? Was that a different 12VHPWR scandal?

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4. ◴[05 Jul 25 02:54 UTC] No.44469791[source]▶
5. bobmcnamara ◴[05 Jul 25 02:55 UTC] No.44469795[source]▶
Contact resistance is a problem.

Another problem is when the connector is angled, several of the pins may not make contact, shoving all the power through as few as one wire. A common bus would help this but the contact resistance in this case is still bad.

replies(1): >>44469801 #
6. ryao ◴[05 Jul 25 02:57 UTC] No.44469801{3}[source]▶
A common bus that is not also overheating would cool the overheating contact(s).
replies(1): >>44469809 #
7. alright2565 ◴[05 Jul 25 02:59 UTC] No.44469809{4}[source]▶
It would help, but my intuition is that the thin steel of the contact would not move the heat fast enough to make a significant difference. Only way to really know is to test it.
8. ryao ◴[05 Jul 25 03:11 UTC] No.44469854[source]▶
I thought that the contact resistance caused the unbalanced wires, which then overheat alongside the connector, giving the connector’s heat nowhere to go.
9. AzN1337c0d3r ◴[05 Jul 25 05:55 UTC] No.44470380[source]▶
They don't just specify 12 smaller cables for nothing if 2 larger ones will do. There are concerns here with mechanical compatibility (12 wires have smaller allowable bend radius than 2 larger ones with the same ampacity).
replies(1): >>44470568 #
10. kuschku ◴[05 Jul 25 06:39 UTC] No.44470568[source]▶
One option is to use two very wide, thin insulated copper sheets as cable. Still has a good bend radius in one dimension, but is able to sink a lot of power.
11. chris11 ◴[05 Jul 25 07:19 UTC] No.44470734[source]▶
I think it's both contact and wire resistance.

It is technically possible to solder a new connector on. LTT did that in a video. https://www.youtube.com/watch?v=WzwrLLg1RR4

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12. ryao ◴[05 Jul 25 18:57 UTC] No.44474738{3}[source]▶
Uneven abnormal contact resistance is what causes the wires to become unbalanced, and then the remaining ones whose contacts have low resistance have huge currents pushed through them, causing them to overheat due to wire resistance. I am not sure if it is possible to have perfect contact resistance in all systems.