Mac hardware quick-fire questions

Can I upgrade my iMac 27-inch Late 2014 for HEVC?

The only iMacs with hardware acceleration for HEVC are 5K 27-inch Late 2015 with Skylake chipsets, and all 2017 models with Kaby Lake. Because this depends on the chipset, there won’t be any way to extend support to earlier models.

My iMac is lifeless!

Ensure it’s getting power by using a different socket and mains cable. Reset its SMC by disconnecting all cables, including power, for 15 seconds, then reconnect and wait for five seconds before pressing the Power button. Still no signs of life? It needs repair.