Securely erasing memory
October 31, 2010 1:29 PM   Subscribe

I'm donating a computer to a friend-of-a-relative. Can data be recovered from the RAM or any other part of the computer?

The computer (an older iMac) has a new hard drive which has been completely erased with all sectors written to zero and random-data-overwrite seven times. I am not concerned with the hard drive.

But I am wondering: can data be recovered from the RAM, or another part of the computer? Is such a recovery possible? Is data stored anywhere else besides the hard drive?
posted by anonymous to Computers & Internet (6 answers total) 1 user marked this as a favorite
Technically, yes. But not in such a way that you should worry.
posted by griphus at 1:34 PM on October 31, 2010 [3 favorites]

I am not a solid-state engineer, but I feel pretty confident that it's impossible to recover data from RAM or anything else besides storage media. (CDs, DVDs, hard drives)
posted by KathrynT at 1:35 PM on October 31, 2010

Stored data disappears from RAM as soon as you turn off your computer, because RAM needs to be powered to retain information. There is an attack that can be used to recover data from RAM after the computer has been powered off, but that only works for literally a few minutes after the RAM loses power.

Your computer may have another section of non-volatile storage called PRAM or NVRAM. This storage is used to keep things like your volume settings, monitor configuration, or keyboard repeat rate consistent across reboot. There won't be anything in here besides settings like those, but you can zero these settings as well if you're super paranoid by following the instructions here.

If your hard drive is zeroed, you don't have anything to worry about.
posted by jordanlewis at 1:38 PM on October 31, 2010 [3 favorites]

If your old CRT iMac displayed a single image for a long period of time, it's possible that the image was partially burned into the tube. I also have an LCD screen at work that somehow has a login prompt burned into it.

Unless you were displaying nuclear launch codes on the screen for a long period of time, I wouldn't worry too much.*

*Also, if you did this before upgrading the machine to OS X, you were violating the EULA. Seriously. It's right there in the second paragraph.
posted by schmod at 3:13 PM on October 31, 2010

If you're paranoid, you could clear the ram by overwriting it. Boot up, open Safari, open youtube HD tabs until activity viewer shows you're out of free memory.
posted by stereo at 5:36 PM on October 31, 2010

For a more robust RAM-thrashing, you could use Memtest

but it's really, really, really, really not necessary.
posted by schmod at 6:24 PM on October 31, 2010

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