iMac not starting

[fynearts]

i have an imac 27" that is running el capitan 10.11.2 - this was very recently upgraded from yosemite. It runs a second monitor (a Benq) and has been the setup for a few years now. I also have a few external hard drives attached via USBs.

i need reassurance on something that happened for the first time last night. I usually shutdown my computer every night but didnt do so last night. When i came to my computer this morning it would not restart. The second monitor when switched on said something about 'no connection' (different words i cant remember).

the machine was completely non-responsive. i went through the plugs and cords - all looked fine. the wall switch was all as it should be. i unplugged the machine and carried it to another plug and it started up fine. i brought it back to its desk and plugged it back in, plugged all the paraphernalia back into the imac and its fine now. started up and its been going fine.

any ideas? i would just like to make sure it doesnt happen again by doing the right thing.
would running a diagonistic or checking out the logs show anything?

thanks in anticipation

 

[honestone]

"Strange" electrical issues can be a challenge! But on the surface, I'd say you are OK, especially if it has not happened again.

But, if you want piece of mind, you can do some "detective" work. First, are you doing backups to an external device? That is critical, as it will have a bearing on the "type" of detective work you can you.

 

[fynearts]

"Strange" electrical issues can be a challenge! But on the surface, I'd say you are OK, especially if it has not happened again.

But, if you want piece of mind, you can do some "detective" work. First, are you doing backups to an external device? That is critical, as it will have a bearing on the "type" of detective work you can you.

thanks for your reply honestone - what kind of detective work?

 

[honestone]

There should be a (hidden) Recovery HD partition on your internal drive. It gets installed by the OS. You can boot to that, and run Disk Utility form there to 1) Verify and Repair the Volume (ie, top) level, and 2) Verify and Repair the Partition (ie, second) level. But, you need to answer the question about backups. (I assume you do not have a more robust disk maintenance/repair program like Disk Warrior or TechTool Pro).