When Ubuntu is in suspend mode, power led is blinking.
Is there a way to turn it off?
This is hardware specific. If you cannot change the setting in the BIOS of your PC, the next way would be to remove the LED connector from your mainboard, which would effectively turn off the LED completely.
You could also try to hibernate instead of suspend, if that's an option.
Well, I know you are looking for general option.
Some Dell laptops have:
Unobtrusive Mode
When enabled, pressing Fn+B turns off all light and sound emissions in the system. Press Fn+B to resume normal operation.
Enable Unobtrusive Mode: By default it is disabled.
Reference: Dell Latitude 3340 Owner's Manual
I have Latitude E6430 and it works well, power led is off. There are other model I see their manuals on the net like: Latitude E5440, Precision M6800, Latitude E6530 ..
ls /sys/class/leds/
on the machine you're trying to do this? (or is this for multiple machines?) – Fabby Jun 02 '15 at 07:59