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RAM and sleep: how do they work?

  1. Nov 14, 2011 #1
    I have two questions with which I'd appreciate some help:

    (1) What are the pros and cons of leaving my home PC in SLEEP mode instead of "SHUT DOWN" (shut off)... I tend to leavge it in sleep mode for portions of the day and wonder
    if I should bother shutting it off for the night.

    (2) I have a "CPU meter" and it shows my RAM is anywhere from about 25% to 50% full
    when I first turn my computer on....seems about the same when it "awakens from sleep
    as well... Is this typical?? What kind of stuff in stored there? Seems like a lot of this fast access memory is occupied before I begin any activities. And why does the storage vary so much before I begin any activities.

    thanks.
     
  2. jcsd
  3. Nov 14, 2011 #2

    D H

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    The biggest advantages of sleep versus shutdown are that (a) it takes a lot less time to wake up than it does to reboot and (b) you lose all open sessions with shutdown. I tend to leave my computer on unless I really do not want to touch the dang thing the next day.

    Your computer has a number of memory resident programs that open at startup or login and close at shutdown or logout. The core OS, the display manager, your anti-virus program, etc. As far as varying activity, your browser and anti-virus program are big suspects. Many are huge memory hogs that tend not to release resources, and getting worse as vendors update their products with little care of what those products do to computers that are a year old or older. My anti-virus program is in a sense a computer virus.
     
  4. Nov 14, 2011 #3
    Dh..very helpful....
    Is there any difference in power use or wear and tear between SLEEP and SHUT DOWN??

    I can tell that my hard drive is off in each case so I'm assuming either state has wear and tear during shut down and start up only. Is there any evidence hard drives tend to fail at such times??...say, like light bulbs tending to burn out with the initial surge of current before the filament gets hot...or gas or diesel engines wear before oil pressure rises????
     
  5. Nov 14, 2011 #4

    D H

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    Science Advisor

    Your hard drive, assuming it was built sometime in this millennium, is designed to be started up and shut down a lot. The arguments regarding wear and tear that some raise is a red herring. Your sleep mode should shut down the disk drive, and almost everything else -- including your monitor. If you are using a screen saver your computer is not going to sleep. Your computer in sleep mode should draw only a tiny bit of current to needed to keep memory alive.

    One disadvantage of putting your computer to sleep as opposed to shutting it down is the quality of your electrical supply. You need not worry if you have a very expensive UPS that maintains a very high quality supply. Keep in kind that a good UPS costs more than your computer. If you are using a $10 surge protector you are getting what you paid for.
     
  6. Nov 15, 2011 #5
    Junk science was demonstrated in elementary school science. Spontaneous reproduction was proved when a dry lake filled with water and spontaneously generated life. A conclusion proven by observation. Not tempered by well proven facts. Observation is one reason for popular urban myths.

    Amber traffic lights that flash all night long are first to fail? Nonsense. Green and red fail quickly. Amber rarely fails. Because light bulb life expectancy is determined by hours of operation and voltage. Power cycling is irrelevant. Red and green illuminate much longer - fail faster. The light bulb industry even has equations to define science with numbers. Unfortunately your conclusion comes only from observation - also called junk science.

    Well, manufacturers claim that power cycling can cause disk drive failure. Then we add what must always exist to have any conclusion. Numbers. A worst (IBM) drive I every saw was rated for 20,000 power cycles. That means restarting a computer seven times every day (even weekends and holidays) for ... seven years. Most drives are rated for 39 years. Yes, power cycling is destructive as another has also noted. Once we temper that subjective fear with numbers, then speculation becomes irrelevant. Or do you plan to be using that computer for another 20+ years?

    Any conclusion based only in observation is junk science. A subjective conclusion is why propaganda and other lies are so effective.

    Use hibernate rather than shutdown or sleep. If you cannot find hibernate, then read the manufacturer's owners manual or Window's Help. Meanwhile, stop worrying about fears generated by wild speculation, popular urban myths, hearsay, and observation.
     
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