THE CRUNCH
A hardware hacker known as Kate has turned a roughly $3,000 Nvidia CMP-170HX cryptomining card into a card with 20% more FP16 performance than a stock $20,000 A100, using voltage glitching to unlock the GPU's factory-disabled features. The CMP-170HX is a mining card built on the same GA100 silicon as Nvidia's data centre A100, but with most of its VRAM and shader modules fused off at the factory.
The trick targets the card's eFuse controller, an array of 16,384 one-time programmable fuses that Nvidia uses to disable parts of the chip that tested poorly, so they can be sold as lower-end models. Normally these fuses are read-only for users, but Kate built a simple circuit board around an $8 STM32G4 microcontroller to intercept the PWM signals sent to the card's VRM controller, forcing voltage glitches on the GPU power line. By repeatedly reading the fuse controller's status during these glitches, she reached a state where its security flags allowed writes through.
The reason an 8GB card can yield 80GB of VRAM is that the GA100 die physically contains all the HBM2e memory; the surplus is simply switched off at the factory. The 8GB variant is based on the 80GB version of the chip, while 10GB cards come from the 40GB design. After modding ten cards, Kate found nine with the full 80GB working and one with 64GB usable. Unlocking every shader module gave her FP16 FMA performance 20% beyond a stock A100, which she attributes to chips often carrying more usable modules than the 108 on the spec sheet.
An existing soft-mod called CMPunlocker already unlocked some features, but left VRAM capped at 40 to 64GB, many shader modules locked, and PCIe bandwidth limited to 2.0, with no ECC, NVLink or multi-instance GPU support. Kate's volt-mod removes those limits too, and her best card runs at PCIe 4.0 with the full feature set. Fuse writes are irreversible, so she was careful to keep any shader modules previously marked defective switched off.
Kate says she is publishing the research now because someone else independently found the same issue. She has informed Nvidia, though there is little the company can do about cards already sold. Prices may shift as awareness of the mod spreads.