The mass production rhythm of High Bandwidth Memory (HBM) has changed. To meet the demands of core customers, HBM supply chain manufacturers have commenced production ahead of schedule before the completion of certification. Samsung Electronics and SK Hynix initiated mass production of HBM4 before the full completion of testing to meet NVIDIA's HBM demands. Since establishing its mass production system in September last year, SK Hynix has been producing in quantities as required by customers; Samsung Electronics also entered the risk mass production stage of HBM4 in the second half of last year and began mass production and shipment in February this year. Manufacturers are taking this step to align with the release of NVIDIA's AI accelerators and avoid short-term shipment constraints. However, risk mass production also comes with significant costs, as inventory pressure will be borne by suppliers if demand fluctuates or products encounter issues. Currently, the HBM4 testing for NVIDIA by both manufacturers is still ongoing, and NVIDIA's official Qual testing is expected to conclude by the end of the first quarter.