  Power consumption will be a key constraint on the future growth of
Distributed High Throughput Computing (DHTC) as used by High Energy Physics
(HEP). This makes performance-per-watt a crucial metric for selecting
cost-efficient computing solutions. For this paper, we have done a wide survey
of current and emerging architectures becoming available on the market
including x86-64 variants, ARMv7 32-bit, ARMv8 64-bit, Many-Core and GPU
solutions, as well as newer System-on-Chip (SoC) solutions. We compare
performance and energy efficiency using an evolving set of standardized
HEP-related benchmarks and power measurement techniques we have been
developing. We evaluate the potential for use of such computing solutions in
the context of DHTC systems, such as the Worldwide LHC Computing Grid (WLCG).
