An Nvidia 12VHPWR adapter cable with a chip in it.
This issue has been around for a long time, but I only just got an RTX 40 series card and so it is all new to me. Please let me know if I have something wrong below…
I received my new RTX 40 series GPU and it came with an Nvidia branded 3-into-1 12VHPWR adapter cable for the power supply. Sadly, my Corsair power supply only came with 2 PCIe power cables, so I needed an additional PCIe cable to make the Nvidia adapter work properly. But if I purchased that cable, I’d end up with an octopus like mess of 4 cables connected together just to get power to my GPU! Another option would be to "daisy chain" one of my existing PCIe cables, like this:
An ugly mess that isn't a good idea.
Clearly, I should just get one cable to replace this messy bundle.
But!...
- Of course, the power supplies are not all the same... some use different proprietary pinouts! This is why many recommend using the Nvidia adapter provided with the GPU with the cables that came with the PSU, and I suspect the chip in the adapter cable helps check things too.
- Wait… there is a chip in the Nvidia octopus adapter cable that comes with the GPU?! Apparently, the Nvidia 3-into-1 adapter cable that comes with the GPU actually has a chip in it that tells the GPU that all three ends at the PSU are plugged in and supplying the proper voltage etc. But the aftermarket cables do not have that chip and I suspect just hard-wire the sense lines. I read that this is fine, as long as you actually properly plug the adapter into a properly spec'd supply. Also, note the Nvidia adapter cable seems to connect all the positive wires together, and same for the ground. The aftermarket cables only seem to short adjacent PCI2e wires together at the 12 pin GPU connector.
- I had remembered there was a connector problem when these RTX 40 series cards first came out: connectors at the GPU were melting! People were not plugging in the connectors all the way, or they were bent hard near the GPU and that was pulling them out or weakening the connections. Also, original cables were soldered to the connectors, a potentially bad practice for power cables. So you want to get a quality cable, with crimped connections. And don’t stress the cable by bending it harshly at the connectors.
- You can now get cables with a 90 degree (right angle) connector at the GPU, so the cable doesn’t have to bend hard, an issue in smaller cases like mine. The right angle can bend up toward the backing plate or down toward the cooling fins. Note that if you want a right angle (90 degree) cable you have to make sure your connector on the GPU is not recessed and decide if you want the right angle to bend up toward the backing plate or down toward the cooling fins. Some GPUs may only fit a cable that goes one way, bent up or down. The cable manufacturers seem to call these “A” or “B” variant/type cables. Note that if you choose the bend so that it goes over the latch (B), it may be very hard to remove the connector from the GPU because the connector and cables will be in the way. Choose carefully.
- You also need to decide if you need a 2-into-1, 3-into-1 or 4-into-1 cable. This is determined by the power requirements for your GPU. The manufacturer CableMod claims that a 2-into-1 cable is enough to provide a full 600W, but there is little reason to use less than a 3-into-1 cable if you need full power*.
- Can you get one that matches the specific connectors and wiring on your power supply?
- Are you are OK with using a cable without a chip?
- Do want a right angle (90 degree) connector on the GPU end of the cable, and if you do, what way should it bend and will it fit?
- Do you need a 2-to-1, 3-to-1 or 4-to-1 cable?
top: ugly assembly of Nvidia adapter connected to 2 Corsair PCIe cables.
bottom: aftermarket 3-into-1 12VHPWR cable with 90 deg connector.
Of course, there is a new power supply cable standard that just came out… don’t be surprised if the next generation of GPUs use a new connector called the “12V-2x6” connector. Supposedly this new connector will be backwards compatible with the 12VHPWR one.
*From the CableMod web site:
DON’T PCI-E PORTS ONLY PROVIDE UP TO 150W PER PORT? HOW IS IT THAT A 3 X 8-PIN (OR 2 X 8-PIN FOR THAT MATTER) CABLE CAN BE SUFFICIENT TO POWER GPUS THAT REQUIRE UP TO 600W AT PEAK? In truth, an 8-pin PCI-e port on modern PSUs can supply over 300W of power each (up to 342W, depending on model). Thus, two 8-pin PCI-e ports are more than enough to provide the required 600W. We provide both 3 x 8-pin and 4 x 8-pin versions of this cable for extra redundancy. **Please note that all 8 Pin PCI-e plugs need to be plugged in for the cable to function properly. If you order a 2 x 8-pin, 3 x 8-Pin, or 4 x 8-Pin to 16-Pin, make sure that all of the 8-pin connectors are connected correctly to your PSU.
source: https://cablemod.com/support/#12vhpwr-pcie-gen-5-atx-3-0
