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I ordered a pair of new DDR3 RAMs, I will install them to the empty RAM slots once they arrive.

What would happen if I hibernate my PC, then install the new RAMs, and then wake it up from hibernation? Would the system give an error message, or would it wake up alright? Do I need to shut down my PC before adding the new RAM units?

Of course, restarting PC after such a critical hardware change is important and affordable; and I will definitely do so. But I'm just curious about this, I am asking this question out of curiosity. I want to learn how the system would behave if I were to not restart it.

OS: Windows 7 Ultimate x64 SP1
Mainboard: Gigabyte P55A-UD3R, rev 1.0
RAMs: DDR3, 1333MHz

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Shutting everything down is A Very Good Idea<sup>TM</sup> It's not one of those hotplug changes. – Fiasco Labs Feb 18 '13 at 23:50
Easy enough to try with a VM and see. – ckhan Feb 19 '13 at 3:46
@Ramhound The goal is to see how Windows reacts to suddenly having more RAM (ie. when waking up from hibernate). A VM would be a perfectly valid way to experiment with this. – Burhan Ali Feb 19 '13 at 21:58
@FiascoLabs this is not about plugging RAM into a running PC, but about the reaction of a hibernated OS. – gronostaj Feb 20 '13 at 8:06
@Ramhound Good point about the VM. The other thing is technically correct, but a hibernated machine can be unplugged from the mains power. – Burhan Ali Feb 20 '13 at 14:55
up vote 36 down vote accepted

You will get an error message from the Windows Resume Loader on restart. You will get this nasty warning:

Your system's memory configuration has changed since it entered hibernation. If you proceed, the data needed to resume from hibernation will be lost. To preserve this data, turn off the system power, restore the orginal memory configuration and reboot the system. Otherwise, press to delete restoration data and proceed to system boot menu.

If you continue without restoring the original memory configuration, you will get roughly the same affect as if you had removed power suddenly rather than hibernating.

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Did you try it? – Louis Rhys Feb 19 '13 at 6:19
Why would I bother, I've got better things to do with my time. And understanding what happens during a hibernate save, trying it is like sticking a hairpin in a power outlet, from experience of similar situations, we already know the results. The hibernate snapshot is not being restored to the same memory configuration, the OS dumps it and starts from scratch. – Fiasco Labs Feb 19 '13 at 8:04
I would also ensure that the computer is unluppged (or battery removed), as there otherwise will be some power in the system (stuff like WOL, keyboard wakeup, etc). – Holger Feb 19 '13 at 8:42
@Holger - I install DIMMs routinely with mains power connected and have never had trouble. (I know, it is bad form for the reasons you mention, but...) – Shinrai Feb 19 '13 at 15:15
@Shinrai Sure it will work, but there is a risk and I just wanted to point that out. I've also changed a lot of stuff without wearing a antistatic wrist strap, but once day I'll probably break something :) – Holger Feb 19 '13 at 15:29

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