Hi all, I have Mac Pro Late 2013 D300, shipped with Mavericks 10.9.5 and works fine without any problem for 2 years (i'm buying it at early 2015). Two weeks ago, I update to El Capitan 10.11.5, the problem is it can not turn on after shutdown. Press power button, its dead, and only turn motion sensor light. Press power button for 10 second and more, nothing happen. Can't solve with "standard" SMC Reset. The Mac Pro can turn on ONLY if disconnect power cable for 15 minutes or more, then plug in, then wait for 10 second or more. When press power button, the motion sensor light is active. Already trying PRAM reset after turn. But it's not working. Trying to clean install latest Sierra, the problem still there. Not try to get back 10.9/10.9.5. I'm not sure, this related to software/firmware or hardware. Now, I never shutdown, just sleep, and sleep. No problem with wake after sleep mode. Any suggestion? Software/firmware or hardware? Maybe power supply problem? Clean install 10.9.5 and never update to Yosemite/El Capitan/Sierra? Bad news, it's not under warranty (if hardware issue). No Apple Service Provider at here, only Premium level Apple Store. But there are some technician with "soldered component skill level" for Apple product. They succeed replace graphics chipset my 15" MBP 2011 with discrette graphics issue. Thanks and really sorry about my English.