Why is it bad to shutdown your Mac?

As a corollary to the other thread. Usually, I shutdown my mac each night before bed. When I get up in the morning, I turn it on and leave it on all day, if I'm at home. If I go to work, I turn it off, and turn it on again when I get home.

So, my question is, why is the above bad? That is, so many folk here seem to leave their machines running all the time baring updates or glitches; so, why is it bad to shutdown a mac each day (for the record, I have a Mac Mini, as should be known from my info...)?

I don't remember anyone saying it was "bad" to shutdown (I don't recall anyone saying "bad"). It's just more convenient to "sleep" the computer.

- Nick

Mencelus said:

As a corollary to the other thread. Usually, I shutdown my mac each night before bed. When I get up in the morning, I turn it on and leave it on all day, if I'm at home. If I go to work, I turn it off, and turn it on again when I get home.

So, my question is, why is the above bad? That is, so many folk here seem to leave their machines running all the time baring updates or glitches; so, why is it bad to shutdown a mac each day (for the record, I have a Mac Mini, as should be known from my info...)?

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Hello - I'm w/ Nick and the others who leave their computers on - I only turn them off if going out of town for a few days or more or if a re-boot is required. In fact, turning your computer off & on frequently (like daily or more) might just be more harmful to its electronics, i.e. electrical and sudden heat changes - not my area of expertise but some good discussion HERE about the pros & cons of the two choices. Dave

RadDave said:

In fact, turning your computer off & on frequently (like daily or more) might just be more harmful to its electronics, i.e. electrical and sudden heat changes - not my area of expertise but some good discussion HERE about the pros & cons of the two choices. Dave

Click to expand...

I've read good discussions of this subject many times. I did not follow your link, but I bet I've read it before. I have not, however, seen any hard data supporting the theory that the off/on cycle harms the computer. If someone knows of a scientific study on the subject, by all means, post a link to it. But, for more anecdotal input, I have done what the OP describes for 3 computers that I've owned over the course of the last 22 years or so and have only replaced a unit due to software issues. The off/on cycle, for me, has been a non-issue.

Mencelus said:

As a corollary to the other thread. Usually, I shutdown my mac each night before bed. When I get up in the morning, I turn it on and leave it on all day, if I'm at home. If I go to work, I turn it off, and turn it on again when I get home.

So, my question is, why is the above bad? That is, so many folk here seem to leave their machines running all the time baring updates or glitches; so, why is it bad to shutdown a mac each day (for the record, I have a Mac Mini, as should be known from my info...)?

Click to expand...

A lot depends on how stable your power is in Budapest. Does the power fluctuate a lot (up and down, brownouts, etc.)? Generally, turning an electronic device on and off imposes wear and tear on the power supply and other components. Most electronic equipment nowadays is built to withstand that, but wear and tear does build up over time. Keeping the machine on at all times in sleep mode avoids that type of wear and tear for the most part. However, if you live in an area where the power is not stable, then turning off the machine when you're not around might be best. Only you can decide that. You might want to invest in a good UPS.

The biggest risk to electronics is the surge of current at power-on. That first "inrush," as it is called, can overload devices which are cool and quiet from being off and more vulnerable to the sudden current and attendant heat change. Here is a link to a Wikipedia article on inrush current. Note the sentence, "Power converters also often have inrush currents much higher than their steady state currents, due to the charging current of the input capacitance," in the first paragraph. The power supply in your Mac is a power converter. Inrush is also a challenge for motors, such as the motor in the hard drive. Now Apple (and just about every other manufacturer) does put in place inrush limiters to minimize the inrush and to allow the components most vulnerable a chance to stabilize without being hit with the high current flow from power-on inrush, but those components can also fail. Inrush is not a huge problem anymore, but it does happen. Consider the incandescent bulb--most failures are "blowouts" when the bulb is in a lamp that has just been turned on. That's inrush.

On a sidenote, folks who renovate old radio equipment use what is called a variac to bring voltage slowly up to full so that the tubes, capacitors and other components can warm slowly and fail (if they are going to) more gracefully. Just plugging in an old tube radio and turning on the switch can result in some pretty spectacular results if the capacitors in the power supply are dried up!

Show us where it said 'never shut down'? The advice was to sleep the Mac sleep rather than a daily shut down. And I use a UPS (Uniterrupted Power Supply) to prevent that inrush Jake speaks off. One reason why hard drives always seem to fail at boot

Harry, UPSs don't protect from inrush. Inrush is inside the device, when power is applied (turned on or plugged in, for example). UPSs can protect from surges outside the UPS, but when you press the start button, inrush happens inside the Mac. There is inrush protection on the internal circuits, but if that fails, or the inrush is high (big load on USB port, HD a little "sticky" or optical drive) that protection may not work. Leaving things powered up reduces the probability of inrush failures.

There's nothing wrong with turning your Mac or other device off sometimes. It's perfectly fine. Apple suggestion is to sleep the computer most of the time, and the company makes this suggestion for a variety of reasons, including that sleeping has less of an "inrush" than a cold start. The difference in power consumption between the two states is negligible, and in more recent Macs the PowerNap feature relies on the machine being asleep rather than off to do its thing.

As long as you're not turning off your Mac by tapping your foot on the on/off switch on the surge protector and are doing a proper shutdown, if you prefer to shut down by all means feel free to carry on doing so.