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An RTX 5090 owner says a custom daughterboard spread power across the card’s existing 12VHPWR/12V-2×6 connection and two added PCIe 8-pin inputs. The owner reported wire temperatures below 40°C during a 48-hour, 550 W test, but the result is a single user report—not an independently verified or manufacturer-approved solution.
What the RTX 5090 owner changed
Redditor DallasGrave described the modification in a post titled “Solving the 12VHPWR Connector Problem.” The design keeps the GPU’s original power connector in place and adds a pickup PCB soldered to contacts on that header. Wiring from the pickup PCB connects to an auxiliary daughterboard, which accepts two PCIe 8-pin power plugs. TweakTown’s account describes the plugs as attached at the backplate. The arrangement is intended to distribute the load across the original input and the two added inputs, rather than replace the original connector. DallasGrave’s post; TweakTown’s October 2, 2026 report.
What the temperature report does—and does not—show
DallasGrave says the card ran at full load for 48 hours while drawing 550 W, with about 3 A per conductor. The owner wrote: “The card was running full load for 48 hours at 550W and the wires never crossed 40c even at the joint.” Those figures and the temperature observation come from the owner’s post, not a published independent test. Wccftech and TweakTown summarized the report on October 2, 2026. Original post; Wccftech and TweakTown coverage.
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#1 Best Overall
- Compatible with: 12vhpwr power cord connects your new 16 pin(12 power pins+ 4 sense pins) GPU to old 8 pin pcie power supply, with up to 600W output. Works with: RTX 5090 5080 5070 5070ti 4090 4080 4070ti
- Original Standard: Sleeved extension cable is make of alloy copper and tinned for long-term using, Bending resistant and durable
- Do ensure the pins are fully seated, hearing a distinct click and see no gap. A loose connection can cause high resistance, leading to overheating or melting at the connector point
- This is 12vhpwr not new model 12v-2x6. They are both capable of delivering 600W of power. To get the max 600W output, you must ensure that 16 pin port and 4 x 8 pin(each 150W) pice port are firmly plugged without any gap
- Please note that 12VHPWR-1X4 is compatible with most 8 pin old pcie power supply. Standard 8-pin port can reach 150W output
Does this solve the RTX 5090 connector problem?
It is evidence that one owner built a supplementary power-input arrangement and reported a favorable wire-temperature result in one test. It does not establish a general fix for RTX 5090 owners: the measurement has not been independently replicated in the cited accounts, and they provide no evidence that NVIDIA or an add-in-board manufacturer approved this modification. The sources also do not establish durability over time or validate a retail daughterboard or consumer cable kit for this setup.
The design involves soldering a custom board to contacts on the GPU’s power header. The owner’s reported result is not a procedure, compatibility guarantee, or safety recommendation for other cards.
Rank #2
- 2X 8pin to mini12+4Pin Converter cable
- Cable Length: 6.3inches = 16cm
- Replacement for RTX 5080 5090 4090 4080 L20 L40 H100
- You will receive: 1x Cable as pictured
How it differs from the separate TecLab experiment
A separate TecLab project reported in September 2026 used a different RTX 5090 design and a different power-input architecture. TechSpot describes a Galax HOF OC LAB RTX 5090 variant designed for two 16-pin inputs; Tom’s Hardware identifies the card as a Galax RTX 5090D HOF OC LAB XOC. In that experiment, 8-pin connectors were installed directly on the card PCB, replacing or bypassing the stock connector arrangement. Tom’s Hardware says the modified card was tested up to 900 W during a one-hour livestream. TechSpot’s September 10, 2026 report; Tom’s Hardware report.
That direct-to-PCB setup is not DallasGrave’s supplementary daughterboard, which retains the original header and adds two 8-pin inputs through auxiliary boards. The two reports describe different cards, wiring, and tests; their temperatures should not be compared as if they were measured under matching conditions. Tom’s Hardware’s discussion also gives 150 W as the official rating for a standard PCIe 8-pin connector. That rating, cited in the separate TecLab coverage, does not establish a safe power rating for DallasGrave’s custom board or another owner’s cable arrangement. Tom’s Hardware report.
Quick Recap
Best Value
- 4x 8pin to mini12+4Pin Converter cable
- Cable Length: 6.2inches = 16cm
- Replacement for RTX 5070 5080 5090 4090 4080 L20 L40 H100
- You will receive: 1x Cable as pictured
Rank #4
- 【Notice before shopping】To order a correct power cable for your PSU and GPU, please make sure your PSU has the PCIE 8Pin ports. And we recommend you had better confirm the RTX 5090 / 5080 / 5070 / 5070Ti / 4090 / 4080 / 3090 Ti GPU's requirement of the output wattage of PSU.If this cable is not suitable for your power supply or you are not sure about your port type, please feel at ease to contact with us. Don't plug and unplug by force
- 【For RTX 3090Ti, RTX 40 and 50 Series】Fasgear PCIe 5.1 16(12+4)pin male to 4X8 pin female sleeved extension cable is made for GeForce RTX 5090 5080 5070 5070Ti 4090 4080 4070ti 3090Ti GPU. That means, this 12VHPWR PSU cable can extend length and work well with the original power cable to get stable and reliable performance. Note: This GPU sleeved extender cable is not fitted for 12pin GeForce RTX 3090 Series & 8pin RTX 4070 GPU. Only support 12+4pin GPU like RTX 3090Ti, RTX 40 and 50 Series
- 【Up to 600W Output】Fasgear 12V-2x6 PSU extension cable supports up to 600W output. The plug terminals of the graphics card cable are made of alloy copper and tinned material, which can bring stable and higher currents. NOTE: This extension cable requires four unoccupied 8-pin PCI-e ports on your power supply to properly function. Connecting fewer than four connectors to your power supply may cause system damage.
- 【Neat and Tidy】Fasgear 40cm 4x8 pin GPU riser extension cable, compared with the original 10cm power cable, can make your DIY computer system neat and tidy. With 4 transparent cable comb acrylic clips, it is convenient for you to manage this sleeved extension cable cord. Thus, this extension cable can make the appearance of the computer system more beautiful. Note: This cable is a 12V-2x6 sleeved extension cable. And it needs to be worked with the original power cable.
- 【16AWG Tinned Copper Wire】Fasgear 12V-2x6 PCI-e 5.1 extension cable contains 16AWG tinned copper wire. Compared with the standard 18AWG power cord, this updated 16AWG tinned copper wire can bring stable voltage transmission and higher power output. Meanwhile, this tinned copper can prevent oxidation. As for the 12+4pin connector, 2 of 4 pins are connected with power wires while another 2 pins are GND wires
Rank #3
- 【16Pin GPU Power Cable for RTX 4070Ti】PCIE 5.0 16 Pin with dual 8 Pin Connector, this psu extension cable is mainly designed for Geforce RTX 4070Ti GPU which has the 16 Pin connector. Please Noted: This 16Pin sleeved modular cable is only suitable for 16pin GeForce RTX 4070 4070Ti 4070 Super Series GPU.
- 【Better Protect Your Graphic Cards】Made of alloy copper and tinned material, the plug terminals of the graphics card cable can bring more stable and higher currents with no heat on the plug and cable, which can avoid Graphic Card overheating due to the adapter is bent too much or frequently loose or connect. With 2X8Pin connector, the gpu extension cable can support 400W to 450W output, peak power up to 450 Watt.
- 【Stable Voltage Transmission with 16AWG Tinned Copper Wire】Using with the upgraded 16AWG tinned copper wire, this PCIE 5.0 extension cable can ensure more stable voltage transmission and higher power output, up to 450W. Unlike the original thick and stiff power cord, this GPU extension cable adopts the high-density flexible protective sleeve and nylon braided fiber.
- 【Neat and Space Saving】With the length of 14 inches, the 2x8 Pin psu extension cable enable you to have more room to create a more neat and tidy computer system for those tight or smaller cases. The included 4 transparent cable comb acrylic clips can help you better mange the extension cord for a clean look of your computer system.
- 【Warm Tips before your Purchase】Your package will include 1 Pack 16pin(12+4) to 2x8pin PCIE 5.0 12VHPWR adapter sleeved extension cable(13 Inch-Black). As a newborn brand, we care customer most.Provide high quality products and prompt customer service is our goal. If you receive any defective chargers or have any other problems of our products, please feel free to contact us.
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