Corsair’s PSU Chief Weighs in on Melting RTX 4090 Adapters

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(Photo: Jonny Guru)It’s now been several weeks since we first heard of RTX 4090 power adapters melting. Sadly, there’s still no word from Nvidia on why it’s happening. In light of this dearth of information, many have attempted to solve the mystery on their own. Corsair’s head of power supplies Jonny Guru, who used to review PSUs for a living, has now delivered his hypothesis after extensive testing. According to his data, the situation might be a simple matter of what folks in the IT world call “ID10T.” That is, he thinks connectors are probably melting because they weren’t plugged in all the way.

As a quick refresher, the first big report on this was from Igor’s Lab. They do good work, and had seemingly uncovered a glaring error in Nvidia’s design of the 4-into-1 PCIe adapter that ships with every RTX 4090. That error is a lack of solder on the pads that connect the power cables to the connector on the PCB. In his testing they were easy to break off when the cable was bent at an extreme angle; a common occurrence as gamers tuck the cables out of the way.

After he published his report, other tech sleuths examined their adapters and found they didn’t match Igor’s. Instead of a poor soldering job, they found it was actually quite robust on the adapters they had. This leads to a theory that Igor might have tested pre-production adapters. Both Gamers Nexus and Jayztwocents attempted to force their adapters to melt, to no avail. Even with the adapter intentionally broken, it refused to melt. This flies in the face of Igor’s report entirely. It’s possible Nvidia did its homework on the adapter, after all.

The adapter used in Igor’s Labs’ tests might have been a pre-production unit. (Image: Igor’s Lab)

Jonny Guru decided to take matters into his own hands after emailing Nvidia about the issue. According to his blog post via Tom’s Hardware, Nvidia told him it’s “still testing.” With that resource being a dead end, he grabbed several adapters and began testing. He inserted three PCIe power cables along with a temperature probe into each. This allowed him to torture test the cables and monitor the temperatures where the adapter fits into the connector on the PCB. Instead of RTX 4090s, he used a board with severe bends and conducted all-night torture tests.

An incorrectly inserted PCIe power adapter. (Image: Jonny Guru)

Like other testers, he intentionally tried to get an adapter to melt and was unsuccessful. Even when he broke one of the outside power leads completely off, the adapter never melted. Also, the probe he used never reported temps higher than 53C. This lead him to reexamine the photos people posted online of melted adapters, and he came to a simple conclusion: People aren’t plugging them in all the way (above). He notes this is not necessarily their fault, because the new adapter is apparently difficult to insert fully. This is due to the new sideband rails that communicate with the GPU, he says. He also notes we’re seeing more melted adapters versus ATX 3.0 cables just because the former are more prevalent.

In the end, he says his opinion is the adapters are actually fine. They are just very difficult (emphasis his) to insert fully. Overall, it does seem like there is sufficient solder, and the connection is very solid. Even if it’s bent, or damaged, nobody has been able to force it to melt so far. Still, more testing is required before this can be confirmed. A word from Nvidia would certainly help too, but we’re still waiting on that. For now, if you have an RTX 4090, make sure you can’t easily unplug it once it’s inserted. If you can just pull it out, it’s not fully seated.

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