Worried About the GeForce RTX 4090’s New 12VHPWR Power Socket? Don’t Be

The launch of the Nvidia GeForce RTX 4090 family of graphics cards has ushered in a new generation of graphics technology. (Check out our review at the link for evidence of that.) Not only is this mega-card a big step for Nvidia, but the GeForce RTX 4090 is also the first to employ the new 12VHPWR connector for powering graphics cards. With 12VHPWR likely to become a universal standard in the next few years for powering GPUs, this a momentous occasion.

This new interface between your GPU and your PC’s power supply has a number of benefits over the old PCI Express six-pin and eight-pin power connectors that the industry has been using for more than a decade now. A good deal of misinformation, however, has been spreading around about this new power connection, and that needs to be addressed. If you have any concerns about the 12VHPWR connector, or simply want to know what it is capable of, keep reading.

Power Limits: They Are Higher Than You Think

Before we dive into the new 12VHPWR power connections, let’s first go over the old PCI Express six-pin and eight-pin connectors we have been using for over a decade now, and what they are capable of. It’s widely believed that the PCI Express six-pin power connectors have a maximum power limit of 75 watts, and the eight-pin ones have a maximum power limit of 150 watts, but this actually is not true.

When the PCI Express interface was first conceived a little more than 20 years ago, PCI Express x16 slots were designed to handle 75 watts of power passing from the motherboard to graphics cards. At the time, this was more than sufficient for graphics cards, but when this limit was eventually reached, it became necessary to add more power through another connection. At first, traditional four-pin Molex power connectors were used for this, before the industry transitioned to the six-pin and eight-pin connectors that we know today.

(Photo: Zlata Ivleva)

The widely recognized power ratings associated with these connectors were established more from convenience and ease of remembering than from any real, concrete limitations. The motherboard’s PCI Express x16 slot could handle 75 watts, and so the six-pin power connectors’ power limit was simplified to match it at 75 watts, and the eight-pin connectors’ power limit was made to double that. When it comes to transmitting power, however, the physical characteristics of the material used matters. In general, thicker, heavier-gauge wires can handle more power than thinner, smaller ones.

On the topic of 12VHPWR, we talked with Corsair’s lead power supply engineer, Jon Gerow, who is better known in the PC enthusiast community as JonnyGuru. As JonnyGuru, Gerow, before he joined Corsair, was a much-respected longtime reviewer and expert analyzer of PC power supplies. (JonnyGuru.com, alas, is live no more, living on only in the Internet Archive(Opens in a new window).) He made the point to us that it logically didn’t make sense that the wires in the six-pin power connection would only be able to carry as much power as the far, far smaller wires in the PCI Express connector.

(Credit: Zlata Ivleva)

For now, it’s best not to get overly worked up about the exact true limits of these power lines. The simple truth is that it varies somewhat. The size and quality of the wires matter, as does the hardware inside of the power supply delivering that power. You may well have a lower limit with a cheap off-brand power supply than with a high-end model from a major manufacturer like Corsair, Cooler Master, SilverStone, or Thermaltake. As long as the power supplies were designed and built properly, the limit of the six-pin power connector is going to be higher than 75 watts. And these power lines are supposed to be tested, for safety purposes, to handle significantly higher power loads than that.

Though they aren’t accurate, the six-pin’s 75-watt power limit and the eight-pin’s 150-watt power limit has stuck, and it is often used by graphics card companies. Those limits are extremely safe and conservative, and there isn’t any harm in following them, except that you may end up using far more cables and connectors than you truly need in a given situation.

The New 12VHPWR Connector

It’s this last issue—having too many cables in play—that the new 12VHPWR connector chiefly works to overcome. This is especially the case for graphics cards, as all those power connectors eat up valuable real estate on the board that could be used for other components. The 12VHPWR connector officially supports up to 600 watts of power, all through a 12-pin connector that’s similar in size to a single eight-pin PCI Express power connector.

(Credit: Michael Justin Allen Sexton)

Before the RTX 4090 launched, a few concerns were bruited about regarding the safety limitations of this connection, as well as about powering GPUs with it using an adapter. But these aren’t really things worth worrying about. The first of these red flags was raised by PCI-SIG(Opens in a new window), which warned of a potential issue when using the 12VHPWR connector. But the issue encountered occurred during something resembling torture tests that they were performing on the 12VHPWR.

During the test, the cable used was purposefully torqued so as to make a less-than-ideal connection in which not all of the pins were connected as securely as they should be, and some of the pins weren’t connected at all. The power connection continued to work, though, as safety tolerances built into the cable enabled it to soldier on even without a solid connection on all pins. The cable was then placed under an excessive load of 660 watts and used continuously at this load for over 10 hours, before it finally failed.

(Credit: Michael Justin Allen Sexton)

Clearly, this showed the cable and connection are capable of failing. But so long as you make sure your cable is connected properly and you don’t run it overloaded for several hours on end, it’s not something you should ever have to worry about.

Another red flag was raised about using eight-pin PCI Express-to-12VHPWR power adapters. This time, the alarm was raised by Wccftech(Opens in a new window), which tested a number of these adapters. They recorded more than 150 watts of power being pulled through these eight-pin PCI Express power connectors when only two or three eight-pin power connectors were used. The adapter with just two eight-pin PCI-E power connectors was recorded as pulling around 300 watts of power from each connector.

They were absolutely right that this was happening, but according to Gerow (and the Molex standard related to this connection), this is perfectly fine. This is the reason we started this article off detailing the commonly accepted limits of these power connectors and explaining that though 150 watts is often stated as the limit of the eight-pin power connection, it is actually far higher.

(Credit: Corsair)

You may want to tread carefully if you have an off-brand power supply, but Corsair told us that all of their power supplies would have this scenario covered without issue. They also told us that the difference between ATX 2.0 and ATX 3.0 power supplies really isn’t as significant as some are making it out to be. Many of the improvements in ATX 3.0 were incorporated into earlier revisions of ATX 2.0, with the most notable new change being the 12VHPWR connector. Long story short, you really don’t need to be worried about having an ATX 3.0 power supply or about pulling too much power through your “old-school” PCI Express power connectors if you buy a new graphics card that uses 12VHPWR.

Gerow also related the following interesting tidbit about the development of 12VHPWR, which hints at where this standard might be going in the future. “At the beginning of testing the new 12VHPWR connector, we were asked to go ahead and test with two 12VHPWR connectors as well, testing of at least 900 to 1,200 watts,” he said. “Of course, I can only speculate what that would be used for. Perhaps for something over 600 watts, they’d want the extra connector for safety reasons.”

He continued: “I know we’re not only the only ones being told to do this, as I’ve already seen renders of power supplies out there with two of the 12VHPWR connectors on the modular interface when using a one-to-one 12VHPWR cable. And there have been discussions about adding a second 12VHPWR connector to the ATX 3.0 test plan.”

The 600-watt power limit for 12VHPWR is enormous, and so far no graphics cards are pulling that much juice. But if indeed using two of these connectors has been discussed, that points to the likelihood that one day we will see graphics cards using two 12VHPWR connections. Graphics cards pulling down upward of 1,200 watts are hard to fathom at present. And if the massive Nvidia GeForce RTX 4090 is any indication, such cards by themselves would likely be the size of entire small computers. But it will still be interesting to see what comes of this power struggle in the future.