Should I Leave My Mac On All the Time or Turn It Off?

1999 – Should I leave my computer on all of the time? Some people say keeping it off is better for the computer, and others say keeping it on is better. Can you please clarify this issue for me?

There are positives and negatives on both sides of this issue. I will talk about both and then give my suggestion.

Reasons for leaving your computer on:

  • Turning your computer on and off sends a jolt of electricity through your computer that can potentially burn out your power supply.
  • SCSI hard drives tend to run quite warm, and leaving them on for a long time and then turning them off can cause minor damage to the drive, and eventually it may stop working.
  • If you use your computer frequently, leaving your computer on may be more convenient.
  • If you have a large number of extensions, startup may take a long time – leaving your computer on all the time avoids this.

Reasons for leaving your computer off:

  • If the power goes out while your computer is on, you may cause damage to the data on your hard drive, and there is a slight chance of hardware damage as well.
  • If your computer runs very hot and is not in an area with good ventilation, then heat damage could potentially occur with the hard drive or other components.
  • The longer your computer is on, the more likely it is to be effected by power surges and possible lightning strikes.
  • The longer your computer is on, the more likely your memory will get corrupted. This means you will have to restart your computer every now and then. Turning off your computer each time you are done with it usually avoids this problem.

My suggestion: Unless you run a server or use your computer very frequently, I would turn it off when it’s not in use. Most people do not use their computers long enough for the SCSI hard drive to get hot enough to cause damage. The potential risks of power surges, lightning strikes, and power outages have more effect on a computer that is turned on (remember, however, a computer that is turned off can still be damaged by lightning if it is plugged in).

If you decide to leave your computer on, follow these tips to make sure your computer lives a long, healthy life:

  • Purchase a UPS, a backup power device. (See Protect Your Mac for more on UPSes and surge protection.)
  • If you overclock your processor or have a lot of hot-running devices in your computer, make sure there is good ventilation in both the computer and the room that the computer resides in.
  • Make sure you check frequently to see if the fans in the computer are still running. A burnt out fan can mean death to your power supply in a matter of hours.
  • If you are running a server or simply have your computer hooked up to a phone line, make sure that not only the power to the computer, but also any other cables to the outside world, are protected against power surges and lightning strikes.

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