The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →An RTX 5090 owner says a prototype board adds two auxiliary 8-pin power inputs alongside the card’s original 12VHPWR connection. The builder also reports wires stayed below 40°C during a 48-hour, 550 W run. That is a self-reported result, not independent validation: the report says the test method was not specified, and long-term durability remains unknown.
How the add-on board is described
Reddit user u/DallasGrave describes a pickup PCB attached at the card’s original 12VHPWR header. It feeds a separate board with two 8-pin PCIe inputs, while the original 12VHPWR connection remains in use. In other words, this design supplements the existing connection with two additional input paths; it does not replace the 16-pin connector.
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The builder wrote that “the 12VHPWR connector is still used but the individual conductor current and temperature is dramatically reduced.” That is the builder’s explanation of the design, not an independently verified finding. [Reddit post; Wccftech report]
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What the reported 40°C result does—and does not—show
u/DallasGrave reports about 3 A per conductor and says the wires, including at the joint, stayed below 40°C during a 48-hour full-load run at 550 W. Wccftech’s October 2, 2026 report says the Reddit post did not identify the test method. No independent lab result for this prototype is established by the cited coverage.
#1 Best Overall
- 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
A temperature reading under one reported set of conditions cannot establish long-term durability, failure behavior, compatibility with other cards, or safety. Wccftech explicitly says further sustained-load durability testing is needed and does not claim to know how durable the modification is. The evidence therefore does not show that the connector problem has been solved.
How that compares with one RTX 5090 model’s power specification
RTX 5090 board-partner specifications are not interchangeable. Gainward’s 2025 Phantom GeForce RTX 5090 data sheet provides a model-specific reference, not a universal requirement for every RTX 5090.
Rank #2
- 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
| Gainward Phantom specification | Value |
|---|---|
| Total graphics power | 575 W |
| Recommended system power supply | 1000 W or greater, ATX 3.x |
| Supplementary power connector options | Either one 16-pin PCIe 12VHPWR or four 8-pin connectors |
These are Gainward’s specifications for the Phantom model; they do not establish that the add-on board is approved for that card or for other RTX 5090 models. [Gainward Phantom GeForce RTX 5090 data sheet]
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallIt is not the same as a separate RTX 5090D PCB modification
Tom’s Hardware reported a distinct TecLab experiment on a Galax RTX 5090D HOF OC LAB XOC: its dual 16-pin connectors were removed and three 8-pin connectors were soldered directly to the PCB. The report describes tests from 400 W to 900 W. That is a more invasive, direct PCB-level modification—not the supplemental pickup-board design—and its reported test range does not validate the Reddit owner’s 550 W run or design. [Tom’s Hardware, September 10, 2026]
Rank #3
- 3x 8pin to mini 12+4Pin Converter cable
- Cable Length: 4.4inches = 11.5cm
- Replacement for RTX 5080 5090 4090 4080 L20 L40 H100
- You will receive: 1x Cable as pictured
Is the add-on board a practical fix for RTX 5090 owners?
Not on the evidence available. The sources do not establish that the featured board is commercially available, independently tested, safe, durable, or compatible across RTX 5090 models. The reported temperature is an attributed observation with an unspecified method, not a basis for recommending that owners reproduce the modification. The Gainward specification is useful only for understanding that particular card’s published power options; it does not endorse a DIY add-on.
Quick Recap
Best Value
- 【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.
Rank #4
- 【Notice before shopping】To order a correct 16pin(12+4) 12VHPWR adapter cable extension for your PSU and GPU, we recommend you had better confirm the RTX 5070 / 5070Ti / 4090 / 4080 / 4070ti / 3090ti GPU's requirement of the output wattage of PSU. If it is not suitable for your power supply or you are not sure what to choose, please feel at ease to connect with us. Don't plug and unplug by force
- 【RTX 5070Ti 5070 4090 4080 4070ti 3090ti】Fasgear PCIe 5.1 16pin (12+4) male to 2x8 pin female sleeved extension 12v-2x6 GPU cable is made for GeForce RTX 5070, 5070 ti, 4090, 4080, 4070 ti, 4070 (only for 16pin interface), 3090 ti GPU. That means, this cable can extend the length and work well with the original power cable to get stable and reliable performance. 【NOTE】 This GPU sleeved extender cable is not compatible with the GPU with 12pin or 8pin power connector, such as GeForce RTX 3090 and 8pin RTX 4070 GPU
- 【Up to 600W Output】Fasgear 12v-2x6 PSU adapter 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 2 unoccupied 8-pin PCI-e ports on your power supply to properly function. Connecting fewer than two connectors to your power supply may cause system damage. For RTX 5080, 5090 series, it is recommended to use 3x8 pin or 4x8pin for higher stability
- 【Neat and Tidy】Fasgear 30cm 16pin gpu cable to 2 x 8 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
- 【16AWG Tinned Copper Wire】Fasgear PCI-e 5.1 extension 12vhpwr 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.
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