Nvidia RTX 5090 Astral owner builds a tool to shut down the PC before the 12V-2×6 cable burns
An owner of an Nvidia GeForce RTX 5090 graphics card from ASUS (ROG Astral series) grew tired of worrying about the safety of their card. The user developed a tool called 12VHPWR Guard that automatically shuts down the PC if current imbalance is detected on the 12V-2×6 power cable connector.
How the protection works
The software runs in the Windows system tray and reads current measurements for each of the six pins on the power connector every half a second. If one pin remains above 9.5A for 15 seconds straight, the tool forces the PC to shut down.
To function this way, the hardware must support per-pin current sensing. This feature is mainly available on premium cards such as the ASUS ROG Astral series. The developer stated that 12VHPWR Guard directly reads the ITE IT8915FN monitoring chip installed on supported ROG Astral cards over the GPU's I2C bus via NVAPI, with HWiNFO shared memory available as a fallback.
All I2C access is read-only. The developer also notes that the tool uses only about 1% of one core and 35MB of RAM. Readings were validated against HWiNFO at idle and under ~500W gaming load, with per-pin readings agreeing within 0.02A.
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