Why Are NVIDIA’s RTX 4090 GPUs & 12VHPWR Connectors Melting?

​​​​​​RTX 4090 is the latest graphics card from NVIDIA. It is a huge GPU and is the fastest graphics card ever made. When overclocked, it needs 600 watts of peak power, most of which is delivered through a single power connector.

However, that huge power draw is causing a significant issue. According to reports, the plastic housing of the power connector is melting after extended use, causing damage to the connector on the RTX 4090 as well. But why are the connectors getting melted, and is there anything you can do to stop it?

What Is a 12VHPWR Connector?

12VHPWR connectors are developed by PCI-SIG, the community responsible for standardizing peripheral component I/O data transfers. The community has representatives from NVIDIA, AMD, Intel, and a few other companies.

12VHPWR 450W and 600W adapters and gpu socket
Image credit: NVIDIA

The 12VHPWR Connector has six 12v pins and six ground pins. It also has four sensing pins, two are which are used to let the graphics card know about the maximum available power at the SMPS. The standard cable offered by NVIDIA has four sets of 14 gauge wires to carry the power, the whole thing is called a PCIe Gen 5 power cable. While a standard Molex connector can do well for up to 30 mating cycles, the 12VHPWR Connectors are rated for 40 inserts and removals.

Why Do NVIDIA’s RTX 4090 GPUs Use 12VHPWR Connectors?

The previous generation of six and eight-pin connectors served well for NVIDIA’s and AMD’s high-end graphics cards. In the image below, you can see the RTX 3000-Series power connector on the left and the RTX 4000-Series power connector on the right.

Comparison picture of two six pin pcie power connectors on previous generation of NVIDIA graphics cards and the 12vhpwr connector
Image credit: NVIDIA

But the RTX 4090’s significant power requirement of 450 watts (standard clock speed) and 600 watts when overclocked is in a different ballpark. Each eight-pin connector has three 12v pins and can withstand a power draw of 150 watts. It means four eight-pin connectors are needed for an RTX 4090, and that is a lot of space on the PCB of the graphics card. Also, the sense wires in the newer 12VHPWR connector save the power supplies from tripping or burn-outs.

At peak wattage, the six 12v pins of the 12VHPWR connector need to supply 600 watts, or 100 watts each.

100 Watts = 12 Volts x i Amps

i = 8.33 Amps

That’s twice as much current per pin compared to the 8-pin connectors but is within the specifications of the new connector (max 9.5 Amps per pin).

What’s the Problem With the 12VHPWR Connector?

The problem, though, is that the plastic casing of the 12VHPWR connector is melting when the NVIDIA RTX 4090 draws power. The connector on the GPU is melting as well. The pins themselves seem to be fine, and the graphics card is still functioning, but the risk of further damage looms.

The fabric tape wound around the connector and the wire sleeves are fine. Heat is obviously the reason for melting, and unconfirmed reports say that the hotspots are appearing after 2.5 hrs of usage at full load.

Why Is the RTX 4090 Connector Melting?

Hardware reviewers and regular users have presented their views on this issue, and a few common themes have emerged:

  • NVIDIA cable uses just eight wires for the 12 pins
  • Inserting and removing the pins more than 40 times causes degradation first and heat later
  • Soldering the wires to the pins instead of crimping them is a bad practice
  • Bending the wires during installation, particularly sideways, results in detached wires due to the solder wearing off

The last reason is what most users point to. If the soldered joint gets detached, the remaining joints have to take up the additional load of current going through them. This causes heat which can lead to the melting of the plastic housing.

However, they could not replicate the melting phenomenon even after disconnecting a couple of wires altogether. On further inspection, it was observed that:

  1. NVIDIA supplied cables with two different types of wires, one marked as 150v and one as 300v; both are rated for a temperature of 105C.
  2. The way the wires were soldered to the 12VHPWR connector was different; one had four solder joints, and the other, two.

Which of those cables is failing and under what specific conditions is still being observed.

Can You Stop Your RTX 4090 From Melting?

The recommendation is that PCIe 5.0 12VHPWR should not be bent before 35mm to the pin, especially sideways. The cable provided by NVIDIA is short and too rigid to leverage 35mm. If the GPU is mounted directly to the motherboard, it is practically impossible to use the NVIDIA cable without bending it at all.

A 90-degree adapter made by CableMod will be available soon. It is a feasible solution with the added advantage that the additional adapter will melt instead of the pin on the GPU in case of a problem.

03 Picture of 12VHPWR 90 degree adapter from CableMod for RTX 4090
Image Credit: CableMod

The other option is to replace the standard adapter with a quality third-party product. Corsair’s 600W PCIe 5.0 12VHPWR Type-4 PSU Power Cable sells for under $20. It is long enough to bend easily and has 12 wires compared to NVIDIA’s eight.

Both options are proactive measures and a better choice compared to replacing the pin on the GPU, which will be very expensive. The connectors themselves are around $5, but the service cost for replacement will be much higher.

For now, NVIDIA is investigating the problem. It is neither recalling nor replacing the cables for free. If you have faced the melting problem, you can raise an RMA request.

It’s worth noting that crimping has worked without any issues for the previous generation of connectors. However, you cannot crimp the 12VHPWR connector for now!

Picture of a pin crimped to a wire

RTX 4090 and 12VPHWR Connectors Need a Rethink

At 600W, the individual pins in the 12VPHWR connector are practically at their maximum rated capacity. If one pin goes bad, there is no headroom for the others to soak the additional load. Increasing the number of connectors on the RTX 4090 is definitely a good choice.

It is a lucky escape for other GPU makers, though. AMD’s 7000-Series GPUs won’t use the 12VHPWR connector, and Intel announced that while the 12VHPWR is the most significant addition to the ATX 3.0 standard, it won’t use it on their ARC GPUs, either.

Either way, NVIDIA needs to go back to the drawing board and rethink the power draw of the RTX 4090 while using the 12VPHWR connector. A few melted connectors is bad press; something going seriously wrong and causing a fire would be horrendous.

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