I am selling this 5 year old Mac through online. But before that, I am looking to wipe all its data to an extent where it is unrecoverable. The only question is how should I make sure if my Mac is wiped beyond recovery.
Disk utility overwrites the sectors of the hard disk drives using 0s and 1s. 3 Passes indicates that disk utility will overwrite the location with binary numbers in three times. Similarly 7 passes overwrites the location seven times. All these efforts are made to make sure that no data is left out on the drive which can be recovered using a file recovery software. In my above post I told you that Disk Utility will not wipe it's own startup drive since you cannot erase the drive from which OS X have been booted. You have to make a bootable dvd to start the Mac and erase your Mac OS X hard drive. Hope this info helps.
Macintoshes hold their worth extremely well, and it frequently bodes well to offer yours to help pay for the new model you are pining for. On the other hand you may be feeling liberal, and you need to hand it down to somebody destitute. One inquiry rings a bell.