Nvidia CMP-170HX voltage glitching unlock A100 80GB VRAM, Digi Mart USA News: A technician known as Kate has used voltage glitching to turn a $2,500 Nvidia CMP-170HX cryptomining card with 8GB of memory into a configuration that Tom’s Hardware reports is faster than a $20,000 Nvidia A100 with 80GB of VRAM.
The modification builds on the CMPunlocker soft-mod for CMP-170HX cards, which unlocks abilities beyond stock. Kate’s work began with a paper describing how GA100 cards’ microcode could be exploited, and she turned her attention to the normally protected onboard fuse controller.
Fuses are normally blown once at the factory to disable parts of a chip that test poorly. According to the report, the GA100 silicon already includes the corresponding HBM2e memory dies and shader modules, which are disabled at the factory, so the cards can be sold as lower-end models.
The report says the fuse controller can be read to reveal a card’s configuration, and that many features, including VRAM sections, individual shader modules, PCIe 4.0, NVLink and video codec hardware, have related fuses. Kate reportedly described Nvidia’s design as insecure because popping fuses can grant access to more features rather than fewer.
To write to the fuses, Kate reportedly built a circuit board based on an $8 STM32G4 microcontroller to intercept power-control signals on the card. This forced the voltage regulators to produce glitches on the line feeding the GPU, where the fuse controller sits.
Repeated fuse-status reads then allowed the controller’s security flags to permit writes.
Kate reportedly force-disabled shader modules previously marked as defective, because these are physical fuses that cannot be undone. Of the cards she modified, nine reportedly had the full 80GB of VRAM working, while one had 64GB usable.
Unlocking all shader modules reportedly gave 20% more FP16 FMA performance than a regular A100.
According to the report, the CMPunlocker soft-mod alone leaves VRAM limited to 40 to 64GB, keeps many shader modules locked and limits PCIe bandwidth to 2.0, while lacking ECC, NVLink and multi-instance GPU support. The voltage modification reportedly removes these limits, with Kate’s best card running at PCIe 4.0 speed with the full feature set.
Tom’s Hardware reports that a CMP-170HX 8GB currently costs around $3,000 and the 10GB variant around $2,500, while a full Nvidia A100 80GB in PCIe form can reach $20,000 or more. The report notes these prices may change as the mods become better known.
Kate said she is publishing her research because another person independently found the same issue, and she has informed Nvidia, though the company has limited options for cards already on the market.
