On a travel laptop, what stalls AI first on the 18-thread 251HX?

  The power wall stalls it first, memory bandwidth second, and the 18 threads are never the problem. As the smallest HX bin, the 251HX covers short quantized runs with 5.1GHz turbo and VNNI, while its NPU, quoted near 30 TOPS, keeps always-on light duty alive on battery. Sustained jobs meet a chassis that clips power and a memory path with little spare bandwidth, and no thread count rescues that pairing.

  It is a fair buy for light AI on the road plus occasional plugged-in bursts. Anyone planning to base large local models in a laptop should move that job to a desktop or the cloud. Trust the NPU on battery and wake the threads at the wall; flip that order and the experience sours quickly.