What: NVIDIA's RTX Spark "superchip" (unveiled around Computex / Build 2026) pairs a 20-core Grace CPU with a Blackwell RTX GPU that together address one 128GB unified memory pool over NVLink-C2C — the idea this page explains is unified coherent CPU–GPU memory . Why: On an ordinary discrete GPU, any data the GPU touches must first be copied from CPU system RAM into GPU VRAM across the PCIe bus — a copy that dominates the moment a model is too big to fit in VRAM. A shared pool lets the GPU read t