Advice on selling a PC second hand?

Hi all.

I am planning on selling a PC second hand. I'm confident with the pricing and what to set my limit as far as making some money goes, however what I am unsure about is how to go about ensuring ALL of my data and possible credentials from 3 years of use are gone, short of replacing the drives.

Also are there any mandatory quality standards that you have to abide by when selling second hand? (UK) Might sound daft however I have not sold something before to someone I do not know.

The machine is in good condition and functional.

Some people say use tools like DBAN and do a couple full passes

I just use linux:
dd if=/dev/urandom of=/dev/sdX bs=8M
I'll do that at least twice for a hard drive and 3 times for a SSD

You're relatively safe after that.

I'm not sure of UK law, but just say that the system is sold as-is and that there is no warranty expressed or implied.

The data is on the drive always until it's written over , even after a format or partition changes.

All you have to do it write over the data to erase it. So find the biggest file you have , and copy it over and over until it fills the drive 100%. Then all that's on the drive is a million useless copies of the same file.

For the love of god don't listen to this troll. He is either intentionally misleading you, or so incredibly clueless as to be of no help. His suggestion will not wipe your drive.

Use something like CCleaner to completely erase the hard drive. You can use the disk wiper tool to overwrite the entirety of the drive up to 36 times. That ensures that any and all data on the drive that was there can never be read again. When you do only a simple format or even a single pass format, the underlying data can be read if the person knows what they are doing. This is why I recommend you rewrite the drive with that tool to ensure nothing can be read from the drive.

If you have SSD's, you only need to properly format the once on those, as when you properly format an SSD once they old data is gone and unrecoverable.

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I agree with @NetBandit here i use DBAN for my hard drive erasing so i can sell them to my friends or people i know.
Sad part is that it takes about eight hours for the thing to complete on a full wipe. I usually do this because the drives i sell are from people whom worked on tax , credit card info. Works like a charm


Okay thanks, there are 3 drives in total, 2 SSD and 1 HDD.

Can DBAN be used on the SSD's ?


Some people say not to use DBAN on SSDs but I don't trust 'secure erase' programs because they dont actually overwrite the flash. Rather they just tell the SSD controller to reset.

Check out this link

Definetly, i think it is alittle fast because of the flash memory

don't knock it till you tried it lol

Well, depends on how paranoid you are and how important the data is.

Back when I was a lowly tech assistant, the story was that the some British intelligence agencies (or just any agency that handled highly sensitive information) had a process somewhat like this:
1. Wipe the drive completely (set everything to zero)
2. Use a program to overwrite random 1s and 0s to the drive something like 7-9 times over
3. Destroy the drives
4. Grind the drive plates into dust
5. Keep said dust in boxes in a vault.

The longer story involved why each further step was necessary, with the slight possibility of recovering some information from the previous step given proper forensic technology and a lot of time and resources (which, to be fair, a rival COUNTRY might have, and the data might be worth it to them). Whether this was true or not is for you to decide.

On a more practical level and in such a way that maintains the drive so you can sell it, you could go with the first two steps, though honestly you probably won't get much benefit past 3 times overwriting, if even that far.

This is, of course, with Hard Disk Drives in mind, rather than Solid State Drives. The reason for doing all the overwriting on the HDDs had something to do with how a 1 or 0 is actually set when it is re-written to a drive (rather than for the first time), which leaves a technical ability to retrace what was previously written given some really fancy equipment.

I just DBAN(ed)a HDD for the military the other day. Obviously it needed the full DoD 5220.22-M, but from what I've read somewhere, that's actually a waste of time. You really only need to do one wipe.

Some parts lose a lot of value being sold with a PC and sometimes it's worth taking a few parts out before selling, for example, closed loop water coolers and extra hard drives are often worth selling seperately from the pc itself to make more money.

Assuming your SSD supports storage-level encryption, Secure Erase is an incredibly efficient and safe way to wipe the drive. The way it works is that everything on the disk is heavily encrypted at all times and there's a secure area that stores the encryption key. The Secure Erase simply securely removes the encryption key and then does a quick format. Yeah, all of the data is still on there but it's seemingly random bits because you just see the encrypted bits and there's no way to decrypt it since the random key that decrypts it has also been permanently lost.

My experience too, normally I find selling individual components nets you more profit overall.

Easier to find some one who is looking for a replacement this or that than to find some one who wants to buy your specifically configured and equipped PC.

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agreed however selling the case or fans by itself is fuitle hence why selling a system with minimal components can make sense.

I find selling cases on locals sites has always worked out for me, 4 cases in the past 2 years. High-end to low end. Package the fans with the case for cheap and it works out. I think most of the people that have bought them have been people like ourselves building systems for friends and family on the cheap.

Selling fans on their own really has sucked though. I'm likely going to donate mine to the local tech not-for-profit if they take them. If not, to the E-waste recyclers they go.

DoD wipe will safely erase data on old disks.

I would select the Linux ISO and burn it to CD then boot PC with cd drive into the Killdisk wiping software and follow the instructions. I recommend anywhere from 3 passes or 7 passes (extra safe) using one of the listed wiping processes, it can take anywhere between 6 and 24 hours depending on how fast your disks are.

If you have not got access to DVD/CDROM drive then you maybe able to burn the ISO to a USB stick using Rufus or something, You only really need to make sure it has a boot-loader and this Killdisk ISO does.

Until someone figures out how to recover that encryption key. The problem is that this relies on trusting the manufacturer to do what they said without backdoor, or weakness... which we've seen in countless examples, is something that they cannot be trusted to do.

If the Pc is a stock manufactured item, just write the make, model and serial number on a sales receipt. If it has been custom built or modified, write a list of full spec of every part.

If drive is to have Windows or other proprietary software, make sure install keys match any included documentation, and record that on sales receipt too. Would be better to sell it with a completely wiped drive (or no drive) but that would put off any buyer wanting a machine they can just plug in and use.

When buyer arrives, offer to show that the machine is fully functional and will boot to an OS. Even if seller declines you still offered to prove it was a working machine.

Have 2 sales receipts marked "sold as seen" sign both copies and get seller to sign, then you both have a copy of the agreed sale,