The market believed Rubin CPX was dead
@mingchikuo says it is back for 1Q27, and the spec is the story
The 2025 design was Nvidia's own HBM dodge: 128 GB of GDDR7 to make prefill cheap
The revived chip carries 168 GB of HBM4 at Rubin's full 2,300 W, with NVLink cut to 1.5 TB/s at most
Nvidia kept the memory and cut the fabric
Kuo: over 50% of AI inference workload is prefill and KV cache build
At the recommended 1:1 pairing, every Rubin now adds another 168 GB of HBM4
Even prefill pays the tax