Igor's Lab recently published an article discussing Nvidia's melting 12VHPWR 16-pin power connectors on the RTX 4090 and why the power connectors are melting. Igor states that the cause for the melting is due to Nvidia's poorly built quadruple 8-pin to 16-pin power adapter, not the 16-pin connection standard itself.
He says Nvidia's adapter is badly engineered, to the point where it can risk damaging the 16-pin connection. Igor discovered that the thick wires coming from all four 8-pin connectors are wired directly to the six 12V pins on the 16-pin adapter (with the rest being ground pins). That in itself isn't a huge concern, but he says this was done via a very bad soldering job.
The solder is incredibly small and Igor says the base is "..a mere 0.2mm of thin copper with a width of 2mm per incoming wire..." This means Nvidia's soldering contacts could be way too small to keep the 8-pin wires connected even under normal bends, which could lead to spotty connections between the wires. Even using one of the best soldering irons, we wouldn't recommend trying to fix this yourself.
If you look at Igor's images, you can tell right off the bat that the soldering job looks poor. This was obviously outsourced to some other company, but regardless the soldering job looked very messy. Igor goes on to say that just lifting off the enveloping layer of the solder causes the connection to tear immediately.
Based on these findings, we can't help but question the continued use of the included Nvidia 'quadropus' adapters with RTX 4090 cards. If possible, you should replace the adapter with a proper 16-pin cable that's designed to plug directly into your PSU. Barring that, a third-party adapter made to higher standards should suffice. The default adapter — which based on our testing of RTX 4090 cards, is part of the package AIB vendors get from Nvidia along with the GPU and GDDR6X memory — appears to be a primary factor in the issues at hand.
If that's not an option, avoid any and all bends near the 16-pin connector on Nvidia's 8-pin adapter. You'll probably have to take your side panel off your case, but it's better to have an ugly computer than a damaged $1600 GPU.
Igor says Nvidia has already been informed about these issues regarding its 8-pin to 16-pin power adapter, so we should see an announcement by Nvidia regarding a fix for the issue. We suspect Nvidia will likely issue a recall and replace the original adapters with a new version that's much more reliable. After all, any component is only as strong as the weakest link. An over-engineered cooling solution on an RTX 4090 card will do you no good if it has to use a shoddy power adapter.
