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I always hibernate my laptop. One of my friends said that hibernating the computer will cause damage to the RAM. From his point of view he said that suspended RAM data stored on the hard disk will burst into the RAM when the system is turned on and decrease the efficiency & lifetime of the RAM by creating black spots.

Is that true? Are there any other disadvantages to hibernating the computer?

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    It couldn’t “burst in to the RAM” even if it wanted to, because a hard drive or even SSD is several orders of magnitude slower than RAM. ;) – Daniel B Apr 29 '15 at 8:33
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    I have bad news for your friend. Your friend knows nothing about memory in a computer works. If hibernate caused physical damage to computers it wouldn't exist on nearly ever operating system in existence. – Ramhound Apr 29 '15 at 11:00
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    Your RAM can happily shovel around several gigabytes of data per second, all day, every day. Your friend is talking nonsense. – Boann Apr 29 '15 at 11:39
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    Did he say "RAM"? Maybe he meant the SSD? Forcing the OS to page out all the RAM definitely increases the amount of data written to the SSD, reducing its lifetime. – AndreKR Apr 29 '15 at 13:28
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    Computers usually use DRAM so it seems unlikely as the DRAM is constantly refreshed. I means that whole RAM is read and written to about 15 times per second. So it would seem likely that any other read/write would have negligible effect on lifetime. Assume you would hibernate/resume only for 15 minutes each time - you would get 13500 writes of whole memory due to refreshes and 1 due to resume. – Maciej Piechotka Apr 29 '15 at 15:51
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Hibernation will not damage your computer's RAM. In fact, your computer's RAM must continuously rewrite itself during operation to maintain its stored data.

  • When you place your computer into hibernation, any RAM in use is compressed and stored onto disk. When you turn your computer back on, the compressed RAM image is loaded and normal operation is resumed.

  • As with most devices requiring a non-trivial amount of working memory, the type of memory your PC uses is called dynamic RAM (DRAM). DRAM must be continuously refreshed to maintain its contents, and this refreshing is nothing more than rewriting the stored data. Your computer does this up to 16 times a second (every 64 ms). As such, hibernation does not unduly stress the RAM and will not damage it in any way.

  • Your friend may be confusing this with the fact that hibernation involves writing a potentially large amount of data to disk. If the system uses an SSD as a boot disk, frequent hibernation (more than a few times a day), especially if many programs are running, can reduce the lifespan of the SSD, as flash memory does have limited write endurance. In normal usage, this is not a concern as modern SSDs are designed to handle tens of gigabytes of writes per day over five years or more. (Do note that the memory image is compressed as it is written to disk, which itself reduces the total amount of writing.)

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    To assuage any concerns about lifetimes for modern SSDs, see this experiment: techreport.com/review/27436/… – cartographer May 1 '15 at 16:58
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    @cartographer is right. Generally, there's no reason to be concerned about SSD flash endurance unless you constantly write more than one quarter the drive's capacity a day to it every day. Most consumer workloads won't come anywhere near these limits. – bwDraco May 1 '15 at 17:03
  • The entire contents of the RAM are overwritten 16 times a second; whether or not they've changed? From my amateur point-of-view, that seems super inefficient. – Carcigenicate May 2 '15 at 23:34
  • @Carcigenicate that's just the way DRAM works. There are other kinds of RAM that are stable, but they're slower, or significantly more expensive than you'd be willing to pay for RAM. And it's all handled by the memory controller, or even the DIMMs themselves, so it doesn't require any effort on the part of the CPU. – Jay Kominek May 2 '15 at 23:56
  • @Carcigenicate: As I understand it, it's done by the CPU's integrated memory controller these days. Yes, it's inefficient, with DDR3 modules typically drawing anywhere from 2 to 10 watts depending on capacity, speed, and voltage. – bwDraco May 3 '15 at 0:14
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As a matter of fact, your RAM must be discharged from every bit of data at the moment that hibernation takes place. This just empties it the same way as cutting off any energy source.

At wake up, the process is reversed as the RAM will be filled with "on disk" data.

This behavior is just as "soft" as your daily use of RAM when you launch and stop your applications, playing games, editing photos, etc.

If it was not the purpose of RAM to accept such rapid charging and discharging data, then it would not have been created the way that it was.

Continue with your habits or invest in a SSD to speed up your boot times and perhaps prefer to "shutdown" instead of "hibernate" your computer.

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    Or just leave it on forever! – user351189 Apr 29 '15 at 14:43
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    Remove the last paragraph and you'll have my upvote :) – That Brazilian Guy Apr 29 '15 at 15:48
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Your friend has great imagination. But to say that writing data from HDD to RAM can burst your RAM is like saying that driving a Ferrari at 40 miles per hour can damage the engine. It can't because RAM is much faster.

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No, it doesn't damage the RAM. The RAM is rewriting itself during normal operation.

Hibernation does however use the hard disk (defined as writing RAM contents to disk and shutting down the system).

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One thing that the other answers have omitted is that, in modern operating systems, the entire hibernated contents of the RAM are not written back right away upon awakening. Enough is written back to make the computer usable, and the rest is used like a virtual memory cache, with the memory manager deciding what does and doesn't need to be written back to memory--the same way it works when you are just using computer normally.

Windows 8 even takes this further, in that it separates out two different parts of memory and hibernates them into different files. Only the part needed to have the computer running at all is in the hibernation file. The rest is written directly to the page file. In fact, the fast "startup mode" of Windows 8 is actually just resuming from hibernation using the hibernation file, but not using the page file. Hence, your friend is likely using hibernation all the time without knowing it.

The main benefit in not hibernating is just that you start out with a clean slate. (Or cleaner state in the case of Windows 8's fast start up mode). Memory does get corrupted over time. But you deal with the same issue just from leaving your computer on all the time.

The best solution is just to occasionally restart your computer. If you have Windows updates turned on (and you should) you probably do that anyways.

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    This answer could be improved with cited sources. – Jason C May 3 '15 at 22:04
  • "In fact, the fast "startup mode" of Windows 8 is actually just resuming from hibernation using the hibernation file, but not using the page file." This isn't true. "fast startup mode" restarts the user session(s) from scratch, but not the system session. – Jamie Hanrahan Apr 4 '16 at 20:58

protected by nhinkle Apr 29 '15 at 20:29

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