Gamers Nexus may have solved why RTX 4090 power cables are melting

The mystery of melting 12VHWPR connectors in GeForce RTX 4090 GPUs may be due to manufacturing defects as well as improper cable insertion, an investigation by Gamers Nexus published Wednesday has found.

The report by Gamers Nexus relied on both X-ray imaging and scanning electron microscope inspection conducted by a third-party failure-analysis lab on connectors—including a failed one—used in Nvidia’s GeForce 4000-series. We highly recommend watching the full investigation, which we’ve embedded below.

GN editor-in-chief Stephen Burke said that sources at add-in board companies have said the failure risk stands at about “0.05 to 0.1 percent.” He notes Nvidia has yet to release any official findings yet, but Gamers Nexus concludes that any 12VHWPR cable can fail under the right circumstances.

One of the leading causes would be foreign object debris or bits of plastic and metal that are induced in the process of seating the cable, or as a manufacturing defect. Primarily, however, it looks like improperly seating the cable and / or then pulling it at an angle can induce failures.

As a result of the investigation, Burke said several of the previous failure theories can likely be dismissed. One of the early theories was weak solder joints on the adapter cable that could break during cable routing, but an X-ray cross section of a cable with a poor soldering job makes this theory unlikely, Burke said.

Another early theory related to the connector contact design, with one type of contact having two splits versus one split. The theory posited that a single split would keep a better hold of the pin in the connector. Burke said that while the theory looked promising, he was unable to reproduce any failure even after hours of trying to force the splits apart and was unable to force a failure.

Burke also largely dismissed the more recent “two adapter theory,” where, of the two possible adapters in use, one design is lacking. Burke said his findings show this is unlikely as he was able to induce failures of the supposedly superior adapter cable by not fully seating it.

During the testing, Gamers Nexus also removed four of the six 12-volt power plugs from an adapter cable to intentionally feed all of the power through just two single 12-volt connectors and was unable to force a failure.

Gamers Nexus’ report somewhat echoes previous testing by Teclab.net.br as well as Corsair’s director of engineering Jon Gerow who concluded the connector is well over spec’d electrically when properly inserted, but can fail when not fully seated.

Gamers Nexus goes on to demonstrate a 12VHWPR adapter cable melting in a GeForce RTX 4090 card by poorly inserting it. This, Burke says, could happen when a person doesn’t lock the cable down and the cable is further pulled out during cable routing by the person installing the card. You can see evidence of that below in a failed 12VHWPR adapter cable that was provided to Gamers Nexus. The cable shows evidence of damage 2mm to 3mm that may indicate it had backed out of the socket causing high resistance.

Burke, in fact, is able to easily induce the failures and melting by having an adapter cable backed out of its socket while putting pressure on the adapter from one side. Doing this, the adapter reached 302 degrees and melted the adapter cable plug and caused damage to the GeForce RTX 4090 card.

Burke points out that one issue that may have exacerbated the failures is the highly publicized concern over the 12VHWPR connectors in the new cards. Rather than leaving a properly seated plug in place, many gamers may have begun regularly removing the plugs to check for melting, which increased the chances of failure by either either introducing foreign object debris or not fully seating after checking that all is fine.

User error or design error?

With the evidence largely pointing to cables not being fully seated, the question now becomes whether this is user error or design error. Burke concludes that while users bear some of the blame, if the design itself allows so many to experience the problem, isn’t that a design error?

At this point, Gamers Nexus’ report seems to be the most plausible answer for the failures, with the upshot for existing GeForce RTX 4090 GPUs being to make sure they are fully seated and locked in.