Researcher fingerprints identical GPUs using torch.index_add_

A researcher demonstrates that physically identical GPUs can be reliably distinguished using numerical quirks from floating-point rounding errors and atomic operations. By using either a custom CuPy probe or a standard PyTorch index_add_ operation, individual chips can be identified with high accuracy across models like the A40 and RTX 3090. The method survives reboots and load, though the PyTorch fingerprint can be disabled by enabling deterministic algorithms. Open article →