An RTX 5090 owner says a custom add-on board lets a card draw power through its existing 12VHPWR connection and two additional 8-pin inputs. The builder also reports that wires stayed below 40°C during a 48-hour, 550 W run—but the test method was not specified, and that result does not establish the mod as safe or durable.
How the add-on board is described to work
The builder, Reddit user u/DallasGrave, describes a pickup PCB attached at the card’s original 12VHPWR header. That PCB feeds a separate board with two 8-pin PCIe inputs. The 12VHPWR connection remains in use; the modification supplements it rather than replacing it. Wccftech’s report and the builder’s Reddit post describe the arrangement.
In response to a reader asking whether two 12VHPWR connectors were feeding the card, the key distinction is that the described setup retains one original 12VHPWR connection and adds a board with two 8-pin inputs. The available description does not establish that there are two 12VHPWR connectors.
What the builder reported—and what it does not prove
DallasGrave says the conductors carried about 3 A each and that wires stayed below 40°C, including at the joint, during a 48-hour, 550 W full-load run. The author wrote that “The 12VHPWR connector is still used but the individual conductor current and temperature is dramatically reduced.” These are the builder’s claims, relayed in Wccftech’s October 2, 2026 report; the report says the original post did not identify the test method.
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A temperature figure from one reported run is not independent verification. It does not establish performance under different workloads, installation conditions, RTX 5090 models, or extended use, nor does it reveal all possible failure modes. Wccftech says the concept needs further durability testing and does not establish how durable it is.
How this compares with one RTX 5090 model’s power specifications
RTX 5090 power requirements and connector options are partner-card specific. Gainward’s 2025 data sheet for the Phantom GeForce RTX 5090 lists the following; these figures should not be generalized to every RTX 5090:
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| Gainward Phantom RTX 5090 specification | Listed value |
|---|---|
| Total graphics power (TGP) | 575 W |
| Recommended system power supply | 1000 W or greater, ATX 3.x |
| Supplementary power options | One 16-pin PCIe 12VHPWR or four 8-pin connectors |
Those are manufacturer specifications for the Phantom model, not approval of the add-on board. The data sheet does not establish compatibility or safety for this modification. Gainward’s Phantom GeForce RTX 5090 data sheet is the relevant model-specific reference.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.A separate 8-pin modification is not the same design
Tom’s Hardware reported a different TecLab experiment on a Galax RTX 5090D HOF OC LAB XOC: its dual 16-pin connectors were removed and three 8-pin connectors soldered directly to the card’s PCB. The report describes tests from 400 W to 900 W. That is a direct PCB-level modification, not the supplemental pickup-board arrangement described by DallasGrave, and it does not validate it. Tom’s Hardware reported the separate experiment on September 10, 2026.
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What owners should take away
- It is a reported prototype, not an established consumer product. The cited accounts do not establish commercial availability, a verified repair service, or broad compatibility.
- The temperature result is not an independent safety test. It is the builder’s report, and the test method was not stated in the reporting.
- Do not treat the modification as a proven fix or DIY installation guide. The available evidence does not establish long-term durability or safe operation across cards.
- Check the exact card’s documentation. Connector and PSU recommendations can differ by board partner and model; Gainward’s figures above apply only to its Phantom RTX 5090.
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