When is NVLink worth it?

# Summary Nvidia's NVLink bridges for RTX 3090 GPUs ($200-$400) provide significant performance benefits only for specific AI workloads: roughly 30% improvement for tensor parallel inference prompt processing and nearly 3x speedup for FSDP training, while having negligible impact on layer split inference, token generation, and DDP training. The testing revealed that disabling NVLink falls back to slower shared host memory rather than direct PCIe communication, making it difficult to accurately measure NVLink's actual value proposition for consumer GPU setups.