HPC systems are usually designed using the state-of-the-art devices. On the other side, the much larger embedded and mobile market allows for rapid development of IP blocks, and provide more flexibility in designing an application-specific SoC, in turn, providing the possibility in balancing performance, energy-efficiency. and cost. We advocate for alternative HPC systems to be built from such commodity IP blocks, currently used in embedded and mobile SoCs. As a first demonstration of such an approach, we present the Mont-Blanc prototype; the first HPC system built with commodity SoCs, memories, and NICs from the embedded and mobile domain, and off-the-shelf HPC networking, storage, cooling, using standard integration solutions. In this paper we present the system’s architecture and evaluate both performance and energy-efficiency. Further, we compare the system’s abilities against a production-level supercomputer. Finally, we discuss parallel scalability and estimate the maximum parallel scalability point of this approach.