NVIDIA cuts Rubin bandwidth to 19.2 TB/s, below AMD MI455X’s reported 23.3 TB/s

Top News · Unconfirmed · techpowerup.com

If you're sizing GPU hardware around memory capacity and bandwidth, NVIDIA's revised Rubin targets change the comparison with AMD Instinct MI455X. A report citing updated specifications puts Rubin at 288 GB of HBM4 and 19.2 TB/s per GPU, versus MI455X at 432 GB and 23.3 TB/s.

Here's what changed:

• Vera Rubin NVL72's reported aggregate memory bandwidth fell from 1,580 TB/s to 1,400 TB/s.
• AMD Helios is listed at approximately 31 TB of HBM4 and 1.67 PB/s aggregate memory bandwidth, versus approximately 20.7 TB and 1.4 PB/s for Vera Rubin NVL72.
• NVLink's reported per-GPU bandwidth fell from 1.8 TB/s to 1.5 TB/s, with bidirectional bandwidth falling from 3.6 TB/s to 3 TB/s.
• HBM4 pin speed dropped from 11.7 Gbps to 9.6 Gbps per pin.

One catch: the report attributes the cuts to memory-bus and electrical-signaling limits, describing NVIDIA's choice as trading bandwidth for system stability.

Sources: techpowerup.com