Hi,

Welcome to the Community. Press the F12 key at the Dell Logo on startup, select Diagnostics and run an extended diagnostics on your computer. Post back with any error codes. As per the system manual the Subwoofer is located below the keyboard at the top right bottom corner.

Send me a Private Message, click on my user name, add me as a friend, and send me your Service Tag, Phone Number and Address.

Thank you.

Does the noise vary with screen brightness ?

Mooly: No, it I'm pretty sure it doesn't.

Okay, will do.

OK, it was just a thought that it was the screen backlight driver (the electronics) making a noise... it happens sometimes.

Obviously without hearing it it's hard to say what the issue is but I still suspect it could be something along the lines of what I mentioned above. Remember how "old type" TV's could make all sorts of noises from within. It could be a similar type issue caused by high efficiency "switching type" power supplies used internally.

If its as loud as you say then that would be very annoying.

Also, to update: I ran the suggested diagnostics and (after more than 3 hours) was told that all tests were passed.

It's still making the noise :/

It seems this is something that isn't going to be user fixable. As it's brand new I would see what your options are for an exchange.

When it makes the noise, if you then just flick the AC power off so it switches to battery does the noise alter at all ? If so that again points to a problem with the high frequency type power supplies used internally. It doesn't mean there is a component faulty as such and that it will fail, just that a "wound" component (like a transformer or coil) is physically noisy.

Also just trying to cover all bases as its very hard to diagnose at a distance... does plugging headphones in alter anything ? That normally totally and physically disconnects the internal speakers. Just in case the noise was audio related even though it doesn't respond tio the volume settings.

Yeah, unfortunately I think you're right.

To answer your questions: Flicking the power stops the noise, but putting headphones in does nothing.

It's getting more persistent, I'm going to call Dell as soon as I get a chance.

Good luck and let us know how it turns out :)

Hi, 

I had exactly the same problem, an irregular hissing noise while having the laptop connected to a power supply. Dell Diagnostics told me everything was fine. I had the subwoofer & loudspeakers exchanged, this didnt help. In the end the mainboard had been exchanged, since then the hissing didnt appear again. 

That seems to confirm the issue is a "noisy" feritte or wound component. Annoying but not a cause for concern reliablity wise.

I have JUST purchased Inspirion 17R SE like 6hours ago,

And just as I have started and PLUGGED in laptop to AC power the Sub-woofer started some kind of screechy noise (like some one is blowing in to the speaker) or sort of radio disturbance.

This problem starts as soon as I use AC power, and some times even with out the AC

this is VERY strange because I have this laptop for like 10hours now and already it has problems

Dell UK promised to "check it" out on Monday and replace anything that was faulty OR give me new unit (or refund)

Any predictions from someone ?? Why is this happening?

So I ended up taking mine in to be repaired and they "replaced everything" whatever that means. It fixed the problem (that was a about a month ago and no more weird noises).

Sorry that you're having the same issue Venom, it's a pain, especially in a brand new machine.

I bought my Dell Inspiron 7720 in the same Aug 2012 time frame as those in this string and also had and continue to have the rather loud hissing noise they mention.  No performance issues on diagnostics, but annoying.  Wondering how to get this fixed.  Also have keyboard issues since original purchase - some keys don't type unless struck twice.  Been busy and only now getting around to seeing if I can get this taken care of by Dell.