Chosen Solution
Hi, Recently I have been experiencing a phenomenon with with my 5K imac. Whenever I watch a video - either on Youtube, Facebook, CNN etc, the computer will power off completely and will not turn on for quite some time and only with a little finagaling. When this happens I turn the computer over and I can see that there are NO diagnostics LEDS lit, even when the computer is connected to power. I keep having to do a SMC reset, repeatidly. Sometimes it can take over an hour before I can see the first LED come on, then the machine powers on and all four LEDS are lit up. Is this a power supply issue or a logic board issue? Is there any way to get a more definitive diagnostics? I ran the Apple Diagnostic Tool and it does it’s test with no issues reported. I formatted the hard drive and started with nothing else loaded ran Safari on Youtube and it happened again. The other thing I did was I vacuumed the dust out of the bottom. Again no luck. Any help would be appreciated. Thanks!
If the on-board diagnostic LED’s are not lighting that points to a power supply, You need to start there. Do make sure you use a good surge suppressor or a UPS. The newer iMac’s appear to be more sensitive to power issues which damage things. Next time you clean your system don’t use a vacuum! You can zap your system with static. Use can’ed air instead. Update (05/12/2018) I would recommend you install this app: TG Pro You’ll want the full version. It will allow you to see the thermal sensors and fan to see how hard your system is running. I would also recommend you run Activity Monitor it will allow you to see which process is consuming the most processing time and system resources. You may still have a logic board issue here as well! But you need to start with the power supply. Think of it this way… If you don’t have a good foundation you can’t build a strong house.
