We're not diagnosing the thing, so why not enlighten us?
I'm wondering what this could be too.
Well, my wild theory is that what we are hearing is electrical noise... abnormally loud electrical noise. Loud enough that it actually can be heard by human ears or loud enough that it's picked up by something that's capable of making a noise that can be picked up by human ears, if that makes any sense...
Let's think about the possible causes of a computer clicking...
-Mechanical noise - well this is easy to check, press/flex/poke check for noise, inside the computer: check for a thing that clicks (hard drive or optical drive) ... not on these macbooks.... check the screws/pogo pins/mounts/ etc. and finally the only two moving parts on the motherboard assembly... the fans... and if we had bad fans we would hear this noise constantly or we could alter the frequency of clicking by adjusting fan speed... tried it, no dice, i guess we could also disconnect the fans and listen for noise while we wait for the processor to fry itself..
-Noise coming from the speakers, caused by interference from something on the laptop ... this is not easy to rule out... you could plug in headphones and see if you can listen on the headphones, but the interference that causes the noise could be coupling onto the laptop speakers directly so the noise wouldn't be audible on headphones... this is not an impossible thing to happen, i've tried locating the speakers to the best of my ability and it doesn't seem to be coming from there,to rule this out you would have to disconnect the speakers and see if it goes away... (i dont' want/can't open my computer yet, i don't have the torx bit needed to undo the screws and besides it's 40 days old and I shouldn't have to be messing around with it, like a beat up car making mystery noises...)
-the only other noise coming from an electronic board that I know about is something called coil noise...
http://en.wikipedia.org/wiki/Coil_noise there's a wikipedia entry if you want more info, it sounds crazy, but it's actually a fairly common problem with modern electronics specially power supplies (for example some new Mac Pros hum when under load... that's caused by noise in the power supplies and some SSDs also hum when being written to)
Long story short : There's two groups of power supplies on the macbook pros... (well actually a ton, but for simplicity's sake i'm only talking about two.. all modern intel chips are low voltage, (1.8, 1.0, 0.8V) and the magsafe connector supplies 5.7V i think... so the first group grabs the 5.7 v and brings it down to the lower voltages required for the processor/fancy chips.... the second group is located inside the intel processor's package... and grabs these rails to divide/clean them some more...
Now, why does the noise only happen sporadically and why is it not a hum? My guess is that it's somehow related to graphics (which is about 60% of the die on these new intel processors)... modern chips are very good at turning off parts that are not being used. my guess is (and i must stress that all of these things are written are a guess by a paranoid hardware engineer) that scrolling on a long webpage is an operation that requires you to redraw a portion of the screen but it is not "continuous enough" to leave whatever part of the chip does graphics on continuously so you have parts of the processor turning on/off...
idle (while you read)(off) --->scroll (redraw stuff) (on) ---> idle (off) -->scroll (on) --> idle (off)
changing the resolution would require the gpu to work hard for a few miliseconds to redraw everything so this would also explain the other scenario discussed in this thread...
I think the pops might be caused by that part of the chip turning on/off, either the power supplies on the motherboard, or in the processor itself pop when there's a sudden spike on the power being supplied. you know, like coil noise but only when these spikes of activity happen...
the reason we don't hear it when playing games or watching cat videos is that for those activities the gpu inside the processor is working harder so it turns on and stays on, it doesn't alternate...
Lastly why do only some computers seem to do this? Well, not all chips are created equally, when chips there's some variability, that's the reason why some power supplies hum and some don't... this applies to chip and larger components like coils, capacitors,etc. my guess is that we are unlucky and somewhere in our computer there's a component that likes to pop...
As you can see it's a wild theory, and i have absolutely no evidence to back it, It's my gut feeling as an engineer that works designing/testing processors and boards used to test them...
I guess the only way to really rule this out is to open the computer, reproduce the issue and listen for pops on the motherboard and listen really really carefully to see where it might be coming from ... then probe the suspected cuplrit's power input on the motherboard and "see" the noise on an oscilloscope... not an easy thing to do, maybe even impossible since you might not be able to get to right spot to probe it, let alone the fact that it WILL void your warranty.
I also have no will to test this, I'm paying for a premium product so as a bitchy millennial I'll have somebody at apple do the debugging for me while I have apple care
... or if anyone knows anyone at apple tell them to hire me and then i would gladly do it in exchange for some stock, decent salary and 4 weeks paid vacation a year... oh and a mac pro
