SXM
NVIDIA's mezzanine socket form factor for GPUs, carrying full NVLink connectivity and higher power than PCIe cards, and the unit that server and price comparisons are quoted against.
Current numbers
H100 80GB → Rubin Ultra 1TBper-GPU usable HBM capacity trajectory (H100 80GB, B200 SXM 180GB, B300 SXM 288GB, Rubin 288GB HBM4, Rubin Ultra announced at 1TB)
~15–30%AMD hardware-price discount vs comparable NVIDIA SXM parts (the second-source incentive)
~15–30%AMD Instinct hardware price discount to NVIDIA SXM — real only if the realized-MFU gap on your workload is smaller