My Macbook whines and moos, and I wonder what's the best thing to do now. After reading many posts here and observing it myself, this is how I understand it:
The moo: actually consists of two noises, a "...mmmmMMMMOOOOO" when the fan spins up and a "OOOOOooooo...." when it spins down. As fan speed is linear to CPU temperature on the Macbook, it spins up at around 65 degrees. When it reaches more than 80 degrees, it sounds like the Macbook is preparing for takeoff
and the CPU clock is cycled down to protect the CPU from overheating. But the moo just happens in the threshold between 65 and 69 degrees. The CPU heats up by a few degrees, the fan spins up, cools down the CPU in about two seconds, and the fan turns off. That's the moo, and I believe Apple could fix it by setting two instead of one thresholds in the SMC: one threshold (e.g. 65° C) for fan spinup and one threshold for spindown (e.g. at 55° C). This would split the moo in half and make it appear a lot less often. The annoying thing about the moo is not the sound itself, but the fact that it happens every few senconds. So I believe this could be fixed in software.
The whine: as I understand it, it happens when the Core Duo idles. The sound comes from the left side of the Macbook and the power adapter. All the "fixes" people have found cause a little CPU load to prevent the CPU from idling, and that is not a useful workaround as it drains the battery and heats up the CPU to a level where the Macbook starts mooing. I'm not sure whether this can be fixed in software.
As we all have the same CPUs, fans and fan controllers in our Macbooks, I wonder how some people claim they do not have these issues. In my opinion, these issues are not related to faulty hardware, but they are design flaws. In this case it would be pointless to ask Apple for an exchange. It's probably a better idea to return it and wait until these issues are fixed (if ever), and then buy a new one.
I'm not saying everyone who claims to own a quiet Macbook is a liar or a Mac lover unwilling to admit it, but can you people please check again? You must be in a very quiet place and you must have good hearing. I guess many people whithout the whine simply don't hear it as the ear's ability to hear high frequencies degrades with age.
Make sure you check for the whine when on battery, when charging and when fully charged and connected to AC. If you are lucky your hearing is bad enough that you only hear it when you put your ear on the keyboard or the AC adaptor ;-)
To check for the moo: open photobooth and wait until your CPU temp reaches about 65 degrees. Does your fan start spinning up and down? If not what else happens?
After all I really like this machine and it's a shame that these two issues make it almost unusable...
Thanks for your participation!
Christoph
The moo: actually consists of two noises, a "...mmmmMMMMOOOOO" when the fan spins up and a "OOOOOooooo...." when it spins down. As fan speed is linear to CPU temperature on the Macbook, it spins up at around 65 degrees. When it reaches more than 80 degrees, it sounds like the Macbook is preparing for takeoff
and the CPU clock is cycled down to protect the CPU from overheating. But the moo just happens in the threshold between 65 and 69 degrees. The CPU heats up by a few degrees, the fan spins up, cools down the CPU in about two seconds, and the fan turns off. That's the moo, and I believe Apple could fix it by setting two instead of one thresholds in the SMC: one threshold (e.g. 65° C) for fan spinup and one threshold for spindown (e.g. at 55° C). This would split the moo in half and make it appear a lot less often. The annoying thing about the moo is not the sound itself, but the fact that it happens every few senconds. So I believe this could be fixed in software.The whine: as I understand it, it happens when the Core Duo idles. The sound comes from the left side of the Macbook and the power adapter. All the "fixes" people have found cause a little CPU load to prevent the CPU from idling, and that is not a useful workaround as it drains the battery and heats up the CPU to a level where the Macbook starts mooing. I'm not sure whether this can be fixed in software.
As we all have the same CPUs, fans and fan controllers in our Macbooks, I wonder how some people claim they do not have these issues. In my opinion, these issues are not related to faulty hardware, but they are design flaws. In this case it would be pointless to ask Apple for an exchange. It's probably a better idea to return it and wait until these issues are fixed (if ever), and then buy a new one.
I'm not saying everyone who claims to own a quiet Macbook is a liar or a Mac lover unwilling to admit it, but can you people please check again? You must be in a very quiet place and you must have good hearing. I guess many people whithout the whine simply don't hear it as the ear's ability to hear high frequencies degrades with age.
Make sure you check for the whine when on battery, when charging and when fully charged and connected to AC. If you are lucky your hearing is bad enough that you only hear it when you put your ear on the keyboard or the AC adaptor ;-)
To check for the moo: open photobooth and wait until your CPU temp reaches about 65 degrees. Does your fan start spinning up and down? If not what else happens?
After all I really like this machine and it's a shame that these two issues make it almost unusable...
Thanks for your participation!
Christoph
