iMac keeps going to sleep! or...

[ambientdaw]

Trying to transfer and backup large hard drives. I leave the house, come back, and the transfer has not completed. I have all my system preferences chosen accordingly:
no screen saver
Energy Saver = prevent computer from going to sleep automatically when display is off
I DO have "turn display off after one hour", but nothing else clicked in energy saver, like put hard discs to sleep or enable power nap.

Why does the computer stop transferring files? It does look like about one hour of data has transferred. Could "turn display off" be affecting this"
thanks!

 

[ambientdaw]

hmmmmmmmm, "turn display off after-never" didn't help either. I don't understand why its going into sleep, or screen saver or screen lock EVER. I have all those things off. I just unchecked require password 1 hour after sleep or screen save but that shouldn't matter. Why is this happening? Tried to Time Machine this baby, and it stopped halfway through at 250gb.

any ideas?

 

[997440]

Resetting the SMC might cure this. Read about it here : https://support.apple.com/en-us/HT201295

.....
Indicators that your SMC might need to be reset
After you perform normal troubleshooting, these symptoms may indicate that an SMC reset could be necessary:

• The computer fans run at high speed, though the computer is not experiencing heavy usage and is properly ventilated.
• The keyboard backlight behaves incorrectly on Mac computers that have this feature.
• The status indicator light (SIL) behaves incorrectly on Mac computers that have this feature.
• Battery indicator lights, if present, behave incorrectly on Mac notebooks that have a non-removable battery.
• The display backlight doesn't respond correctly to ambient light changes on Mac computers that have this feature.
• The computer doesn't respond to the power button when pressed.
• A Mac notebook computer doesn't respond properly when you close or open the lid.
• The computer sleeps or shuts down unexpectedly.
• .....

 

[ambientdaw]

Resetting the SMC might cure this. Read about it here : https://support.apple.com/en-us/HT201295

oh, brilliant thanks. I didn't think of that.