For hardware HEVC encoding you need an Intel 6th Generation Core processor with Intel HD Graphics, or Iris/Iris Pro graphics GPUs.
You can check ark.intel.com for more details. For example see the Core i7 processors here: http://ark.intel.com/products/family/88392/6th-Generation-Intel-Core-i7-Processors#@All
Processor graphics GPU details are in the far right column. Any 6th Generation Core processor with a processor graphics GPU will work, but performance will improve with GPU level. HD graphics="good", Iris="better", "Iris Pro"=best.
Please let us know if you need any more info.