RTX 5090 Power Limit Hack: VBIOS Flashing Reveals Hidden 660W Potential

In a surprising development within the high-end GPU community, enthusiasts have discovered a method to substantially increase the real-world power delivery of NVIDIA’s RTX 5090 by flashing a third-party VBIOS—specifically, MSI’s Lighting 800W firmware. The technique, detailed in a Reddit thread by user u/panchovix, exploits a firmware-level discrepancy in power reporting to unlock up to 660W of actual power consumption, far exceeding NVIDIA’s enforced 400W limit on standard retail models.

According to the report, the workaround is only viable on RTX 5090 cards equipped with a single 16-pin PCIe power connector, excluding dual-connector BTF (Back-to-Front) variants and certain MSI Lighting models. The MSI Lighting 800W VBIOS, originally designed for a hypothetical high-power reference card, contains a different power calibration algorithm that, when flashed onto compatible cards, causes the GPU’s software monitoring tools to underreport actual power draw. For instance, setting the power limit to 50% in software yields a real power consumption of approximately 300W, while the interface still displays 400W. At 100% power limit, the card draws 660W—nearly 65% more than NVIDIA’s intended ceiling.

Technically, the phenomenon is described by users as an "inverted shunt mod," where the VBIOS misinterprets the absence of a secondary power source (common on dual-connector cards) and compensates by scaling power delivery incorrectly. This results in a higher real power draw than what is reported to monitoring utilities like MSI Afterburner or NVIDIA Inspector. The effect is consistent across multiple power settings, with a linear correlation between set percentage and actual consumption, as documented in a detailed table shared by the discoverer.

While the technique offers compelling benefits for users seeking to maximize performance without additional cooling or power infrastructure, it carries significant risks. Flashing a VBIOS is inherently dangerous; an interrupted process or incompatible firmware can permanently brick the GPU. Moreover, the procedure voids the manufacturer’s warranty and may trigger hardware instability under sustained load. TechSpot’s 2026 review of MSI’s "RTX 5090 Ti"—a rumored but commercially unavailable variant—suggests that MSI’s 800W VBIOS was intended for a non-retail, engineering-grade card, reinforcing the notion that this is an unofficial hack rather than a supported feature.

Notably, the method appears to work only on Windows systems using NVIDIA’s nvflash64 utility, as Linux-based attempts have failed due to memory address errors. ASUS users also report losing one HDMI port after flashing, though those using the Astral-Matrix tool retain power monitoring capabilities. The 800W VBIOS is preferred over higher-tier options (1000W, 2500W) because of its lower minimum power threshold (~300W), making it more suitable for moderate overclocking and efficiency-focused builds.

Industry analysts remain divided. Some view the hack as a testament to consumer ingenuity in circumventing manufacturer-imposed limitations, while others caution against normalizing such practices, citing long-term reliability concerns. NVIDIA has not commented on the phenomenon, and no official support or documentation exists for the technique.

For advanced users with a deep understanding of hardware modification, this method presents a rare opportunity to extract hidden performance from a flagship GPU. However, for the vast majority of consumers, the risks—permanent hardware failure, warranty loss, and system instability—far outweigh the benefits. As GPU manufacturers increasingly lock down firmware access, this hack may represent one of the last opportunities to unlock the full potential of consumer-grade silicon before such modifications become impossible.