In my 12 years as a computer technician, this is one question that certainly makes the Top 10 List of most-commonly-asked questions. Many theories have been proposed over the years to support either side of the debate, and anyone you ask is probably going to have their own opinion.
Today, I'm going to do the research for you, add in a little of my own experience, and try to get to the bottom of this hot topic once and for all!
First, let's take a look at some common arguments you may have heard in favor of either side of the "leave it on or turn it off" conundrum.
Turning off the computer will protect it from power surges.
This just isn't true. If a power surge occurs and reaches a computer, it will cause the same damage regardless of whether the computer is on or off.
This was an issue a long time ago in the early '90s with the design of computer power switches. This problem is completely non-existent today with all PC makes and models.
Leaving a computer on all the time will cause it to overheat.
Computers have cooling systems comprised of heatsinks and fans. This cooling system is designed to regulate the heat—drawing it away from sensitive compnents by using heatsinks—and venting the heat out the back of the computer using the fans. This cooling system will work to keep your computer at a safe operating temerature no matter how long it has been on, as long as the fans are all functioning and you don't block the fans from taking in or blowing out air.
Turning your computer on and off every day will make your computer wear out faster.
This is a fairly big subject in and of its own. This argument stems mainly from the idea that when a computer is running, it heats up. The ambient temperature of the air inside a computer is generally around 80 F, while the temperature of the processor (CPU) can be around 100 F upwards of 120 F. High-end video cards can take it a step further, reaching sweltering temperatures of up to 185 F. Physics 101 tells us that a hot object expands. When your computer is turned off, all those hot components will rapidly cool, and of course physics would have it that the cooling causes objects to contract. This repeated expansion and contraction of the sensitive circuits and connections within your computer is argued to make your computer wear out faster, and ultimately lead to it's early demise.
While the expansion/contraction argument is sound and does have a concrete basis, the risk of this expansion/contraction actually causing any amount of increased wear on your computer is virtually non-existent. If this really were the case, you would expect to see much more of an epidimec with computer failures. You would also expect to similar problems in other electronic devices which heat up. like TVs or microwaves, which you also turn on and off all the time.
Letting the computer run all day will wear out the fans and hard drive faster.
It certainly is true that the fans and hard drive in a computer have moving parts, and moving parts wear down the more they are used. The main reason this is considered a myth, though is that there is no proven, consistent, correlation between any factors that are considered to affect failure rates of these components. In fact, Google did an unprescedented study across hundreds of thousands of their own hard drives in their data centers. This study also lacked any cosnsitent patterns of evidence to support this argument. Fans wear down with time, yet the manufacturers publish expected lifespans that are hundreds of times longer than the typical "useful" age of a computer, meaning this point should be moot. My personal experience has shown that excess buildup of dust in a computer will prove far more detrimental to the lifespan of your computer than letting it run 24/7.
A laptop is different from a desktop and you should always turn off your laptop.
While physically different in size, laptops and desktops all work just the same. A laptop can be left on 24/7, just like a desktop. The only risk here is if you were to leave a laptop on without using its hibernate feature, and put it into a laptop bag, the laptop would no longer be able to vent the heat created by its components and would overheat. Thankfully, most laptops are configured to automatically go into hibernate just by closing the lid.
Turning Your Computer Off at Night
- You can potentially save big bucks in electricity costs, especially if you have many computers. See the "Going Green" section below.
- Rebooting your computer each day gives it a "fresh start", so to speak, and it will generally run more quickly and with less errors.
- You have to wait a little bit longer for the computer to turn on each time you sit down to use it.
- When your computer is off, it won't be able to perform background maintenance such as updating your software, scanning for viruses, or defragmenting your hard drive.
Leaving Your Computer On 24/7
- Your computer will be ready for you to use the moment you sit down.
- A PC that's on will detect when it is no longer being used (i.e., when it's idle) and will use that time to perform maintenance such as updating your software, scanning for viruses, or defragmenting your hard drive.
- Businesses may benefit greatly from leaving their computers on 24/7 you, the user, will be able to access your PC remotely and systems administrators will be able to maintain the computer remotely.
- You may be paying more in wasted electricity than you realize, but this can be mitigated down to the point of being virtually irrelevany by utilizing the power saving features of your computer. See the "Going Green" section below.
- Desktop operating systems like Windows 7, Vista, or XP, generally need rebooted once in a while to maintain stable operation.
One of the great arguments for turning your PC off every day when you're not using it is that it saves you power. This is absolutely true and can amount to more money than you might think!
How much does it cost to run your PC?
We pay for electricity by the kilowatt-hour (kWh). One kWh of electricity is equal to 1000 wats (one kilowatt) being used for one hour. Iowa has some of the best electricity prices in the country, averaging only 7.6 cents per kWh. In other states, costs can be as high as 17 cents/kWh. Lets take the national average of about 10 cents/kWh.
A Typical computer setup (PC, monitor, etc.) consumes around 250 to 350 watts of power when it's being used. Doing some quick math, this amounts to $307/yr to run one PC ($522 if you lived in Connecticut)! This really is a worst-case scenario, however. Modern PCs are becoming more and more power efficient and some models can come operate on about half the power, which is still over $150 a year! Most of us also aren't actually "using" our computer 24/7, even though it may be left on. This cuts the power consumption even more, but what if you have more than one PC? What if you're a business and you have have ten PCs? A hundred? Thousands?
Thankfully, modern computers are equipped with a plethora of power saving features. Even the designers of the hardware components themselves are striving to make PCs that can do much more while using much less power.
By far, the most important power-saving feature of any computer is it's ability to go into standby or hibernation, also known as "sleeping". Standby mode can cut your computers power consumption from hundreds of watts down to between 2 and 6. Now you're looking at just $5.25 a year or less if you left your computer in standby for the whole year and never even used it!
Even if you leave your computer on 24/7/365, by configuring a Power Plan for your computer, you can have the best balance between instant use of your computer and saving money. A computer in standby uses only pennies more in electricity than a computer that's switched off.
Here is a great article to learn how to configure your computer with the best Power Plan:
The bottom line is that there's no "right answer" here. Do what works for you and best suits how you use your computer!
Personally, my computers—both at work and at home—stay running 24/7, but they're set up with a Power Plan to go to sleep after 10 minutes of inactivity. When I want to use the computer, a quick mouse-shake or key press and I'm at the desktop in about 5 seconds. It sure beats waiting up to a minute or more when you just want to check something on the net really quickly!
To learn more about this subject, check out our other post: Don’t Turn Off Your Computer at Night—Do This Instead!