GeForce RTX 4090 Power Adapter Dissected

Nvidia GeForce RTX 4090
(Image credit: Tom's Hardware)

According to a report by Igor Wallossek from Igor's Lab, (opens in new tab) the included quad 8-pin-to-16-pin adapter with the GeForce RTX 4090 is hackable to allow 600W of power consumption from just three 8-pin PCIe power connectors. But, of course, this is just an experiment in the name of science. We do not recommend you try this on your adapter for obvious reasons. Always use the adapter included with your GeForce graphics card and follow Nvidia's specifications. However, it's worth knowing if someone reverse-engineers this hack into a sellable product online, we should stay away from it.

Nvidia's power adapter is much more than just a power-splitting device. It's an adapter that detects which of the four 8-pin power plugs is active. It allows the end user to run just three supplementary power connections to the adapter to make the card work - but at a lower 450W TDP. With all four plugs connected, the GPU can access 600W if the power delivery system allows it.

Nvidia's power adapter does this by relaying which power plugs are being used, directly to the graphics card via four tiny wires that come with the 12VHPWR power connector. Two of the four wires are active, and tell the GPU whether or not it's safe to boot up the graphics card - depending on how many 8-pin power plugs are connected.

But, interestingly, Wallossek figured out that connecting just the secondary two-pin plug on a 6+2-pin PCIe power connector can trick the adapter into thinking the plug is active. It will trick the adapter into thinking all four plugs are active and activate the entire 600W power budget. To investigate further, Wallossek looked at the individual wires and found that you can do the same thing by shorting the two sensory wires that tell the GPU which power plugs are active.

It is hazardous, can lead to full-blown system failures, and pose a fire hazard from the power adapter due to the wires overheating the plastic plugs. As for the sensory wire hack, this is even more important to note, since this hack can create a triple 8-pin power adapter for the GeForce RTX 4090 instead of a quadruple 8-pin adapter - but with the full 600W power limit active. Again, Wallossek did the experiment to illustrate how we could eventually see dubious adapters on the market. If you ever see a device like this on the market, avoid it at all costs.

Aaron Klotz
Freelance News Writer

Aaron Klotz is a freelance writer for Tom’s Hardware US, covering news topics related to computer hardware such as CPUs, and graphics cards.

  • InvalidError
    The sense pins are simply open/ground signals to tell the GPU whether it can draw 150, 300, 450 or 600W from the plug. Nothing special to it. Ground both sense pins by whatever means you prefer and that tells the GPU up to 600W are available.

    As for 300W from three plugs, the Molex MiniFit spec goes to at least 8A per pin and that is basically 300W per 8-pin connector. As long as the cables and connectors are properly made, there is nothing particularly hazardous about going down all the way to 2x6-pins which is technically the same number of active 12V pins as the 12V HPWR connector using fundamentally the same connector with a different pin count.

    Put another way, the single biggest difference between the "PCIe 5.0" aux connector and older PCIe aux connector is that 5.0 goes up to 100% of the Molex per-pin spec vs 50% previously.
    Reply
  • Orpheus187
    I'm now confused.. forum's and other news sites show Seasonic psu company and others are releasing a dual 8 pin to 12+4 pin... are they scams?
    Reply
  • InvalidError
    Orpheus187 said:
    I'm now confused.. forum's and other news sites show Seasonic psu company and others are releasing a dual 8 pin to 12+4 pin... are they scams?
    Properly made 6-pins cables can handle 300W per Molex spec, it is perfectly fine for PSU manufacturers to push 300W per 8-pins as long as their connectors and cables are made properly. the "75W" rating on 6-pins is the PCI-SIG officially allowing only 25% of Molex's per-pin rating. As I wrote in my previous post, the major difference with 12W HPWR is the PCI-SIG allowing 100% of Molex's per-pin rating.
    Reply
  • Orpheus187
    I see off brand on Amazon but I know to avoid that ... it was the only cable on pre-sale... then like I said , seasonic is making one. I do not know how to get one for my corsair rmx 1000 ... it only came with 3 pcie cables, I do not even have a 4th for Nvidia stock adapter lol ... I really just wish I could get a 1000 watt or more pcie 5 psu but I only see a 850 hela or gigabyte which the later is not up to spec.
    Reply
  • TJ Hooker
    Orpheus187 said:
    I see off brand on Amazon but I know to avoid that ... it was the only cable on pre-sale... then like I said , seasonic is making one. I do not know how to get one for my corsair rmx 1000 ... it only came with 3 pcie cables, I do not even have a 4th for Nvidia stock adapter lol ... I really just wish I could get a 1000 watt or more pcie 5 psu but I only see a 850 hela or gigabyte which the later is not up to spec.
    Each of your three PCIe connectors should have two 8 pin connectors, for a total of six. You can just plug in both connectors on one of the cables to get the 4th connector for the adapter.
    Reply