Question12VHPWR Sense Pins
Question12VHPWR Sense Pins
Uncertain if the right setup is needed. Decisions are up to moderators.
Quick thought: maybe I'm misunderstanding the situation. I purchased a 4x8 to 12VHPWR adapter, with Sense 0 connected to Sense 1. If the diagram indicates both must be grounded for 600W, does that imply my cable is disconnected at both ends? If yes, can I simply use the full 600W capacity?
Here’s what I have:
Specs:
CPU: i7-13700K (Overclocked)
Cooler: Corsair H150 Elite Caprellix 360mm
RAM: DDR4 G-Skill 4000Mhz (4x16GB, Gear1)
MB: MSI Edge z690 DDR4 WiFi
GPU: MSI Gaming Trio 4090 (Custom SuprimX vBIOS)
PSU: MSI MPG A1000G PCIE5
The original message was adjusted to reflect a different tone while keeping the structure intact. The user expressed frustration about outdated information and sought help with a specific adapter issue.
So further explained, I'm assembling a PC for a friend. The 4090 I own (MSI Trio) can handle up to 600 watts, and I've been using it for several months. This card was capable of accepting custom BIOS files using the old TechSpot tool well before the newer version was released. The card includes a 3 x 8 connector, which isn't enough according to my research for a 600-watt setup—only 450 watts is supported.
The power supply doesn't have a 12VHPWR port (as per my design). With the 5090 series, it's rumored and likely that 12VHPWR will be discontinued. Most PSUs with a 12VHPWR typically have fewer PCIe power connectors (usually five, but six are needed). Therefore, I purchased this 4 x 8 adapter, but noticed that pins 0 and 1 are connected together. I expected them to remain open and not grounded. According to my understanding, grounding is what's required for the card to draw full 600 watts. Looking at other similar cables, they also seem to have this issue.
Here is the image above that you couldn't open. (Source)
Can you explain further? If 0 is connected to 1 and there are no other signal wires, how do we ground it?
Went to take a picture and I'm a derp derp.
Sense 0 and 1 are looped into ground. On the connecter. Initially it looked like they were looped to each other.
However this raises a new concern. Specifically the very last paragraph.
Myth Busted: This is how NVIDIA’s 4-way adapter for the 12VHPWR port of the GeForce RTX 4090 really works! | igor´sLAB
Who doesn’t know it, the funny adapter from NVIDIA, with which you can merge four PCIe 6+2 pin cables to be able to run graphics cards with up to 600 watts? If you only connect three plugs…
www.igorslab.de
I believe the point is that the official cable includes safety measures to prevent issues when not all required components are connected. Running 600W through three cables designed for 150W each (total 450W) seems excessive. The IC chip in Igor's cable is intended to alert the video card if something goes wrong, assuming the card responds. Grounding the sense wires with these cables keeps the maximum power at 600W. For better peace of mind, consider using the provided adapter or a compatible power supply from the manufacturer.
There are several issues I noticed, and I'm still trying to figure out what to do next.
The PCIe standard specifies that 8-pin PEG connectors need to handle 150W. That doesn't imply it's limited to that value; in reality, you shouldn't design anything electrical around just the stated rating unless you're attempting to mislead and cause damage. Yes, 8-pin PEG connectors can indeed support more than 150W. Higher quality cables might use wiring capable of safely carrying up to 10A per cable, which equals 120W per line or 360W total. Still, it's not safe to assume any cable will perform this way without confirming its specifications. The actual capability depends on the specific cable you choose.