DGX Spark vs RTX 5090 vs RTX Spark: LLM Inference Performance Deep Dive

This report provides a comprehensive analysis of three distinct NVIDIA platforms for local LLM inference in 2026: the DGX Spark ($3,999–$4,699 desktop AI supercomputer with GB10 Grace Blackwell chip), the RTX 5090 ($3,500–$4,200 consumer flagship GPU), and the RTX Spark (the laptop/compact-desktop variant of the DGX Spark’s GB10 silicon). The central finding is a stark architectural trade-off: the RTX 5090 delivers dramatically higher token generation throughput for models fitting within its 32GB VRAM, while the DGX Spark and RTX Spark uniquely enable inference on much larger models (70B–120B+ parameters) that simply cannot fit in the 5090’s memory, albeit at significantly reduced per-token speeds.