Is this sound/noise normal?

When my V2 M200 enters sleep mode it makes a weird looping sound, i’m afraid that it’s an awful symptom. But I can’t imagine of what.

A video link:

The only thing that occurs is that this is the same initial sound of the startup but in a loop. I don’t know either if it’s normal, but it was always like that (from April 2014).

Mine does not make that sound.. V1

the same sound does my cpu cooler fan when it needs maintenance and cleaning and I see a lot of debris inside your printer. Take out the bottom plate of the printer and look if the fan in your mainboard works ok if not give it a clean and some lubrication.

Definitely not a good sound. It doesn't sound like a stepper (not impossible though) so I second Revitorio's suggestion to check all the fans. 

No, not the fans. Sure, there are a lot of debris but not inside fans, I'm not that insane, at lest not yet.

I fixed it. Was the PSU, a weird relay inside the PSU. What is funny is that this behavior was present since the beginning of the times, since I bought M200 in February 2014.

But as my first 3D printer, I thought it was normal... Only with sleep mode, present in the last firmware, this sound entered in loop, screaming that it isn't normal.

PSU replaced, noise disappeared.