$NVDA $SKHY $MU $005930 - $NVDA reduced Rubin HBM4 bandwidth from 22 to 19.2 TB/s, down 12.7%. - This implies a reduction from approximately 10.75 to 9.375 Gbps/pin. - HGX Rubin NVL8 memory capacity fell from 2.3 to 2.0 TB, down 13%. - NVL8 aggregate HBM4 bandwidth dropped from 176 to 130 TB/s, down 26%. - TrendForce previously reported that HBM supply constraints and HBM4e qualification uncertainty were prompting NVIDIA to reconsider Rubin Ultra memory configurations. > The critical issue may not be whether HBM4 can reach 10.75 Gbps, but whether suppliers can deliver sufficient volume at acceptable yields. > The NVL8 capacity reduction strengthens the possibility of HBM supply or yield constraints beyond simple clock optimization. > A seven-stack configuration remains speculative, and the bottleneck could lie in the HBM stacks or GPU memory controllers. > The 16.7% NVLink bandwidth reduction suggests HBM alone may not explain every specification change. > For $005930, $000660, and $MU, production yield and qualified supply volume at Rubin's required speeds may matter more than maximum advertised bandwidth. > Lower qualification requirements could also reshape competition among HBM4 suppliers.