Citrini analyst questions SanDisk's HBF demonstration: Possible deliberate underestimation of HBM performance

Odaily News, Citrini analyst Zephyr posted on X platform questioning that SanDisk's HBF vs. HBM performance comparison at its Investor Day may contain parameter configuration bias, arguing that the company deliberately underestimated HBM performance in its demonstration.

Zephyr pointed out that SanDisk set total bandwidth for both HBM and HBF at 12.8TB/s, while running the Qwen3-480B-A35B model with bfloat16. Current model inference more commonly uses FP4 or FP8, requiring approximately 240GB to 480GB of capacity.

Zephyr also noted that SanDisk fixed HBM capacity at 192GB per GPU, but 16-layer HBM4E in an 8-stack configuration can reach 512GB capacity with approximately 32TB/s bandwidth—roughly three times the parameters used in SanDisk's demonstration. Zephyr believes these parameter choices result in the company's claim that "HBF requires only 1 to 4 GPUs, while HBM requires 8 GPUs" failing to adequately represent actual performance under higher-spec HBM configurations.