Perhaps a clue consumable power connectors 12VHPWR on GeForce RTX 4090 graphics cards is already close.
As it turned out, Nvidia, together with partners, was investigating this problem and found that there are two manufacturers of the 12VHPWR connector itself, which is connected to the video card. We are talking about Astron and NTK.
Author Igor’sLAB analyzed all this data and found that the NTK connector has a better locking system and uses a single spring contact, as opposed to the Astron design with two spring contacts. At the same time, the NTK connector requires more effort when connecting.
Astron cables are claimed to have less durability and higher resistance than NTK cables, which can be measured with appropriate equipment after 10 connection cycles. Nvidia runs their tests to measure how plug cycles affect resistance, which should not exceed 2 ohms.
At the same time, all this is true for the adapter cables that come with the RTX 4090 video cards. However, there are already cases of contact melting when using new PSUs without any adapters. Whether NTK and Astron connectors are used there in the same way is not yet clear. But if so, then the cause of the problem may have already been found.