A tested procedure for flashing the factory 300 W VBIOS (92.00.6D.00.0A) onto 8 GB CMP 170HX cards went up on the wiki on October 31, 2026, from @darkmaniac7 (lab notes), who flashed eight cards in one night. It matters because most 8 GB cards ship with the 250 W image (92.00.67.00.01), which allows no undervolt.
What the 300 W image changes
- VF-offset range: 0 to 0 becomes -1000 to +1000 MHz.
- HBM clock: 1458 MHz becomes 1728 MHz; SM clock ceiling: 1410 MHz becomes 1695 MHz.
- Power cap: the default stays 250 W; the maximum rises from 250 W to 300 W.
It is a signed NVIDIA image with matching IDs, so nvflash accepts it without an override, per @con3po7016 (August 23, 2026). The driver unlock is not touched, and the 10 GB card has no 300 W image.
Checks, tools and hashes
The recipe uses nvflash 5.867 for Linux and the ROM from TechPowerUp entry 268495, also attached to the page. Check version 92.00.6D.00.0A, size 1,044,480 bytes and SHA256 789e8f8d4c70dc9eb114c9fdcef6ed2d00aedf15a1eca522519de02042818723 first.
The page also lists MD5 and SHA1 and attaches check_rom.py, which recognises a forged "64 GB" ROM that bricks the card at boot. Save a rollback ROM first and keep a way to power-cycle the machine that does not depend on the GPUs.
The procedure
Boot with the NVIDIA modules blacklisted after a cold cycle. Do one nvflash operation per card per boot; a second one fails and writes nothing. Write each card once, restore the driver, cold cycle and verify 1728 MHz and the 250 W and 300 W caps.
The procedure is Proven (reproduced by a second person, or by the lab on its own hardware, with numbers): all eight cards took the image with zero Xids and zero ECC errors over four cold cycles.
Results and risks
At a GPC offset of +160 the lab measured GLM 5.3 Flash about 3 to 4% faster and DeepSeek V4.1 Flash about 6 to 9% faster, at the same power cap.
Several points carry a Warning, the badge for something that damaged hardware or lost data. A +220 offset that passed a 20-minute miner soak flooded Xid 48 and 172 errors a minute into inference, so qualify each card against the engine it will serve. Unbinding the driver instead hung machines, and a failed flash is recoverable only with an SPI programmer on a 1.8 V adapter.
One owner warned against the image after a photo of a burned card; no post ties a burned card to it, per @xanthefin (October 18, 2026). Keep the cap at or below 250 W until your cooling allows more.