Sounds near Magsafe

[Itzamna]

Hello there.

I have my Macbook Pro for like 1 and half month and so far so good. Yesterday my baby cat took advantage of a distraction of myself and decided to make of my power cord a snack.

The computer was plugged in and the power cord seemed to continue to do his job, since the green light kept up and the menu bar status was saying that it was charged. She didn't rip of the cord, but she made some nasty holes on it. Since i was afraid of some sort of short-circuit i turned off the computer and removed the power cord.


I went to a Mac representant here and bought another 85w Power Adapter.

The thing is, since then i notice some very low noise not in the Magsafe but near it inside the laptop BUT those noises only come when on heavy load, like when demanding lots of work from the dedicated graphic card, or on some heavy file transfers. Its not a typical electrical noise or whistle. Its like the sound of a HDD working but A LOT fainter. You need a very quiet room to hear it.

The rest of the time, its very silence...


Now, i honestly don't remember how it was with the other power adapter. So i would like to know your opinion if this is normal or has the other Power Adapter burnt something inside, or if this Power Adapter is mal functioning...


I have the 2.3ghz 17'' MBP with a SSD.

Thank you in advance.

 

[Itzamna]

Another thing, if i unplug the magsafe, the noise goes away.

 

[Lennyvalentin]

Could it be that noise has always been there even before that Mynock of yours chewed on the power cable (obscure geek reference here, I'm sorry), and you just didn't notice until this happened?

Maybe you just paid more attention after the incident.

Anyway, what you describe sounds like 'coil whine', a phenomenon which can occur in DC-to-DC switching voltage regulators like what you have sitting right next to the magsafe connector. Basically the high switching frequency these things work at sometimes cause tiny vibrations in the choke wire windings which the ear can detect, and this noise tends to get more noticeable at higher load, particulary for the much more powerful DC regulators found on PC motherboards and high-end graphics cards.

It's not harmful, or I've never heard of anything bad being caused by it anyway, other than mild cases of irritation.

 

[Itzamna]

Well, i really cant remember if the noise was there or not, but it seems complicated to NOT have noticed it before. I just need to watch a HD movie at youtube to trigger the noise.


After some more testing i noticed that the noise isn't triggered from the heavy load on the graphic card, it comes from heavy load on the network (both ethernet or airport) and, as i already said, on heavy load on the SSD (which is on the other side of the laptop). The noise from the network load is a lot louder then the SSD load noise. The SSD noise is like someone is gently blowing air but with interrupts each few seconds. The network load noise is, as i have described like and fainter HDD working.

Another thing i noted is that the noise is still there if i unplug the power cord, its just very fainter. The noise, when the power cord is plugged is, by itself, faint, but it gets lower when its on battery only.



Probably i'm just being paranoid, but it was a very expensive machine and... You know.... Its my mac... Plus, i'm really afraid that my cat adventure could have ruined something. :/