Common Questions and Issues with your Mac Laptop

From Mac Guides

Operating Temperature

Q: My Mac feels very hot on the bottom! Is this normal?

A: Apple’s metal laptops have long used the chassis as a sort of secondary heatsink. Some warmth on the case is normal, especially if you have one of the older MacBook Pros or a MacBook Air that have the heat pipe/heatsink against the lower case.

Q: iStat shows I have temperatures over 100C! Am I ok?

A: For the moment, you probably are, as the chips will shut down before they overheat, and if they did overheat the system probably wouldn’t boot again. Continuous heating is not good for the chips, though, nor is the stress of rapid temp cycling. You should probably take your machine into your local Apple Store or Apple Authorized Service Center and have it looked at, or at least try resetting the SMC. Generally, you want to avoid temperatures in the 90s Celsius (>190F) or higher, although they won’t cause immediate damage. It should be noted here that when it comes to computer hardware discussions, temperature readings are almost always given in Celsius, even by people who normally use Fahrenheit (or Kelvin). Just a community tradition, apparently.

Q: What are “normal” fan speeds?

A: All MacBook models use a single small “blower” type fans (the technical term is centrifugal fan). All MacBook Pro models use what is basically a pair of MacBook fans. The MacBook Air has a single small blower. ALL the fans should be spinning at all times, but at a slow enough speed that they aren't audible except in a quiet room. A fan that reads 0rpm on iStat is almost certainly defective, and should be replaced immediately. Max fan speed is ~6000rpm. The fans should speed up on their own somewhere between 65C and 90C of CPU temp.

Strange Noises

Q: My Mac is making a humming noise!

A: Some humming sounds are expected from the fans and HDD. All MacBook and MacBook Air models have a single fan near or just to the left of the center of the machine. Both styles of MBP have the “Left Fan” roughly where the “~” key is. The right fan is little different for the two designs. In the older machines, it’s roughly where the “Delete” key is. On the unibody machines, it is roughly around the “6” key. The hard disk in the unibody machines is inside the right palmrest. On the older machines MacBook Pros, it is under the left palmrest. On the MacBook Air, it is under the right side of the keyboard. Also, the optical drive makes a fair bit of noise when it is running. This is also normal.

Q: My optical drive makes strange sounds when I boot or wake up the laptop!

A: This is also normal, it’s just the drive doing some self-tests, or whatever. You will also hear it when you look the drive up in System Profiler

Q: My computer makes a clicking noise when bumped/picked up/moved sharply.

A: What you are hearing the sudden motion sensor “Parking” the hard drive heads to prevent them from scraping the disc due to the impact. Most newer laptops have this feature, and some notebook drives even include it built in just in case they wind up in a computer without it.

Q: My Mac makes a grinding noise when I tilt it!

A: As your manual states, you shouldn’t pick your computer up or tilt it when it is running. I think pretty much every laptop owner has been guilty of picking their machine up and carrying it to the next room or to the other side of the table when its running, but really, put it to sleep or shut it down before transporting it. Especially if it is going into a confined space like a sleeve or backpack.

Expansion Questions

Q: I want to buy more RAM! What do I do? Get it from Apple?

A: Apple RAM is a ripoff. If they’re feeling generous, it might be an ok deal for the first 3 weeks or so after the refresh. Sometimes it’s a ripoff even then. There are many good third parties to get your RAM from, and it will not void your warranty. See the guide for “Understanding Intel Mac RAM”

Q: Does replacing my hard drive void my warranty?

A: If you have a Unibody MacBook, Unibody MacBook Pro, or plastic MacBook: No. If you have a MacBook Air or an older MacBook Pro, well…..Macs aren’t warranty sealed, so technically it’s doable, but it’s a fairly tricky procedure. Visit iFixit[1] for more details.

Other Things…

Q: I SPILLED WINE/BEER/WATER/SODA/COFFEE/HOT CHOCOLOATE/CHAI ON MY MAC!!! AUGGH!!

A: Do NOT panic, do NOT attempt to restart your machine. Read the following for more info:

Spilled_Liquid_On_My_Mac_or_Keyboard

Q: Do I need to “calibrate my battery”?

A: Apple officially recommends battery calibration only for MBPs that don’t get to ‘stretch their legs” normally. If you use yours on the go as part of your weekly routine, you are probably fine, although you can cycle it if you want.