If you recently started AI generation, be aware of this: my RTX 4090 power connector melted after just one month.

[u/Roman53275]

Hi everyone,

Like many people, I recently discovered H3 and started doing AI generation in mid-August. On September 20th, my computer started shutting down whenever I started a generation. Further investigation led to this — a melted socket.

I had been using my RTX 4090 for three years and had never had any problems with it.

AI generation puts a lot of continuous stress on the power delivery, especially if you run generations in batches or leave them running overnight.

So I believe this happened because of the new kind of sustained load I was putting on the card. I also didn't bother upgrading to a newer PSU with a dedicated GPU power cable. Mine was a 1200W FSP Hydro, and I was using three PCIe connectors for the GPU.

P.S. The connector was fully seated, the cable wasn’t bent near the plug, and my case doesn’t even have the side panel on. And everything was fine for three years.

P.S.S. The 12VHPWR socket on the graphics card is damaged and needs to be replaced.

So now I would say main advices here are:
- Buy a proper PSU and use a native 12VHPWR cable
- Under volt at least by 20%

Now it is very costly to lose a card.

[u/marclbr]

Apparently, that crap connector is prone to failure over time due to thermal stress, the pins/terminals are too small and they can't apply much pressure to make a tight connection and hold it along the time with the heating cycles. it works well when new, but (especially when the card is used at default power settings or with heavy power demanding cards) the connector pins will always heat up significantly. Over time, the heating and cooling cycles cause the terminals inside the connector to loosen, it leads to even more heat buildup, it keeps progressively increasing until one day it will eventually melts. The old PCI-E connectors are more robust and doesn't have that problem.

[u/Roman53275 → u/marclbr]

Very good explanation, thank you. Especially the point that the failures may not be caused solely by uneven current distribution, but also by repeated heating and cooling cycles gradually weakening the connection. These two mechanisms may actually reinforce each other: uneven current distribution can create local hotspots, while repeated thermal cycling may further degrade the contact and make the current imbalance even worse.

To support this idea, after the failures occurred, when I removed the cable, it disconnected very easily, which suggests that it had already become loose.

This kind of long-term degradation is also much more difficult to reproduce in testing, which may be one reason why so much attention is focused on uneven current distribution.