Let's Swap

November 12, 2011 7:01 AM

If you have two identical computers, can you simply take the hard drive out of one and put it into the other?

Two identical computers running Windows. One died (It won't turn on. No light, no sound when the power button is pressed. Yes, there is a power supply). They're cheap computers, a couple years old at this point. Not worth fixing, in other words. I'm guessing the motherboard fried or something.

The one that died is the one with extra files and programs. Can I simply take the hard drive out of it and screw it into the other one? Will the programs work?

posted by unannihilated to computers & internet (25 answers total)

Yes - if all the hardware is identical, you should be able to do this without issue. The first time it runs it may do a new hardware scan (and you may need to set up the wireless network again), but otherwise yes -- this is why organizations buy fleets of computers.
posted by k8t at 7:04 AM on November 12, 2011

Mostly yes. However be aware that Windows Activation may detect the new computer is different (based on a few unique identifiers like CPU ID and Ethernet MAC). I don't know the rules for convincing Activation to accept the new machine, but I believe it's possible if you only switch once or twice in the life of the Windows license.
posted by Nelson at 7:33 AM on November 12, 2011

As everyone had said, you should be able to swap them over with only minor complications. It might be easier to just throw the harddisk into the working computer AS WELL as the one that's already in there - that way you can boot your known working computer's own OS, and just have access to the harddrive (and data) from the broken pc as well.
posted by Dysk at 7:42 AM on November 12, 2011 [4 favorites]

If they're as cheap as you say, it may be that the power supply is actually what has failed and led to your problem. Power supplies can be had pretty cheaply (~$40 for what you'd likely need), and are relatively easy to install. It's just a matter of keeping track of what you unplug from the existing PSU and making sure those are all reconnected after install of the new PSU.
posted by EKStickland at 7:56 AM on November 12, 2011

Dysk, would I need to get some kind of external set-up to do that?
posted by unannihilated at 8:06 AM on November 12, 2011

EKStickland, is there a way to figure that out other than just trying to replace it and seeing if it works? I don't want to blow $40 and a bunch of time on this needlessly.
posted by unannihilated at 8:10 AM on November 12, 2011

You may need to switch the jumpers on the back of the HD from "Master" to "Slave" (or "Primary" to "Secondary", or whatever words they PCed it to). Depends on the age of your system, whether you can do this in BIOS, or it must be done by jumpers. Regardless, it's EASY, and there will be a diagram or simple instructions stamped on the HD itself to tell you how to do this.

"Master" (etc) indicates this is the One and Only One HD that the system will boot from, when you next power it on. "Slave" means "any other HD on the system. (More or less... for a 2-HD system.)

Here's a typical dwg (upside down, at the bottom of the picture).

Here's what the jumpers look like, installed (they're already on the back of the HD).

They always go top-to-bottom across the pairs of pins.

Here's how you install them (use your fingernails to pull them off the current pins).
posted by IAmBroom at 8:16 AM on November 12, 2011

unannihilated open the cover to the working computer to see what kind of connection the hard drive has. Older computers used a wide flat ribbon called a ATA and newer computers generally use SATA. The older ATA cables have an extra connection built right into the cable, for the newer ones you'll probably have to buy a spare cable. Installing a drive as a slave is easy peasy.

Or, you can skip over all the scary internal stuff and buy a hard drive enclosure. It's what I did with mine. Whether all your programs will work, or not, when it's running as a slave drive depends on a lot of thing including whether the program used the OS's registry when it was originally installed. Only way to know for sure is to plug it in and try.
posted by squeak at 8:17 AM on November 12, 2011 [1 favorite]

'Absolutely dead' sure sounds like the power supply.
Could you move the power supply from the working computer to the dead one?

Also, note that for computers, 'cheap' and 'identical' may be in conflict--your two 'identical' computers may have identical specs, but differ in what parts they contain (depending on what the manufacturer could get most cheaply when they were made). They may not have identical motherboards, or even plug-compatible power supplies.
posted by hexatron at 8:17 AM on November 12, 2011 [1 favorite]

Your existing HD has a ribbon cable that attaches on one end to the motherboard of your computer. On the other end, it is very likely to have two connectors, spaced a few inches apart. One connects to your Master HD. The other is available to connect to the Slave HD. IIRC, it's important to keep them connected in this order.

Open your computer case, and look for it. Also, there is very likely an empty slot ("bay") for another HD to be installed (or more than one bay). It doesn't matter whether you connect and then install in the bay, or vice versa, as long as the power is off throughout this process.

So, you have jumpers moved (and noted where they were originally, right? In case you have to go backwards...), the cable connected, and the new HD in the formerly empty bay. Turn the computer on.

This assumes that you're moving the HD to a new computer; if you're replacing the HD in your current computer, the new HD will need to take the "Master" connector, and after that, everything is the same. You may need to swap bays to make it all connect, but that's not important - the bay is nothing more than a hold-down shelf.
posted by IAmBroom at 8:23 AM on November 12, 2011

Also
1. Check that the switch on the back of the power supply is 'on', if there is a switch on the power supply.

2. Try using another power cord.
posted by hexatron at 8:24 AM on November 12, 2011 [1 favorite]

Squeak & hexatron also spoke important truths. It's been a while since I swapped HDs.
posted by IAmBroom at 8:24 AM on November 12, 2011

BTW, power supplies are only interchangeable between computers with identical power needs. Since you said they were identical, you should be fine. Even if they do have different components, it's very likely the power needs overall are the same.

The worst that will happen is that there won't be enough power to run the accessories (video board, etc), and the computer won't boot, or will shut down unexpectedly. You won't destroy your computer; it's not like there are 50Vdc supplies out there on some computers that could fry a 10V board (voltages are standard).
posted by IAmBroom at 8:27 AM on November 12, 2011

Oops: What I said isn't strictly true.

BTW, power supplies are only interchangeable between computers with identical power needs.
SHOULD HAVE READ:
BTW, a power supply that is too small may not be switchable to your system. A power supply rated for more power than your system's original supply won't hurt anything.
posted by IAmBroom at 8:29 AM on November 12, 2011

Okay. I'm going to post a couple quick pics of the guts of my computer while I go through your answers. I'm not seeing an additional bay, either on the inside or the outside, which is why I asked if I had to do something externally if I had both hard drives. Another power cord was one of the first things I tried. Nothing. The light on the computer that lights up when it's connected to a power cord lights up initially then goes out. But I verified that both power cords work on the working identical computer.

http://www.flickr.com/photos/69719573@N03/6337838072/
http://www.flickr.com/photos/69719573@N03/6337837128/
posted by unannihilated at 9:10 AM on November 12, 2011

There's a bit of one-upmanship going on here. Yes, you should be able to chuck the drive from one into the other. It's not going to kill anything, just go and try it. Take the cover off both, unscrew the drives and remove the cables, then reverse the operations on the other side. Don't worry about having access to both drives yet, you just want to see if this method will work for your hardware.
posted by rhizome at 10:27 AM on November 12, 2011 [1 favorite]

Ah, I see, that case really doesn't have any extra room in it. I say just go ahead and swap the drives and see. Swapping the power supplies might be a neater solution but they're going to be a lot more work to swap than the drives are (simply because the case isn't designed for easy replacement of PSUs in the same way that it's designed for easy replacement of hard drives).

You can get an external enclosure if you want— those look like PATA drives (parallel-ATA as opposed to the newer SATA, serial-ATA, interface), so any external enclosure that will hold a parallel-ATA drive of that physical size (3.5" it looks like) should work.
posted by hattifattener at 10:38 AM on November 12, 2011

Yeah, this was starting to get a little above me -- I don't know what a PSU even looks like -- so I decided to just go back to the basic idea and just try it since apparently it won't harm anything. I opened 'em up, swapped 'em (there weren't even any cords, it just popped out), fired up the good one, and -- IT'S ALIVE. Now I'm off to make a human centipede.
posted by unannihilated at 11:01 AM on November 12, 2011

There's a bit of one-upmanship going on here.

No, rhizome, there's a bit of several geeks trying to help someone out here. An internet thread isn't the most efficient place to do this, so our answers and suggestions are piling up pell-mell.
posted by IAmBroom at 2:03 PM on November 12, 2011

Thanks for all your suggestions. Fortunately for me, the most simple solution worked.
posted by unannihilated at 2:33 PM on November 12, 2011

An internet thread isn't the most efficient place to do this, so our answers and suggestions are piling up pell-mell.

I see three and a half hours of "Well MAYBE..." followed by satisfaction a half-hour after someone finally said "sure, go for it." There's a such thing as pragmatic geekery.
posted by rhizome at 3:26 PM on November 12, 2011

Nelson wrote: I don't know the rules for convincing Activation to accept the new machine, but I believe it's possible if you only switch once or twice in the life of the Windows license.

If it does refuse to activate over the Internet, activate over the phone. It's an automated system and it, in my experience, always activates, even in the most Piratey McPirate situations imaginable.
posted by wierdo at 4:11 PM on November 12, 2011

rhizome: we have 2 different POVs. S'OK.

...in my experience, always activates, even in the most Piratey McPirate situations imaginable.

Nice to know... hypothetically speaking, wierdo.
posted by IAmBroom at 6:20 PM on November 12, 2011

I do this with a set of Thinkpad A31's. My backup strategy for this particular set of computers is the other computer. Works like a charm.
posted by FauxScot at 6:50 PM on November 12, 2011

As others have said, it should work fine for a standard desktop computer. If you have hardware-based RAID 5 (which is far more common on servers and very rare on home PCs), you run a slight risk of ruining all of your data if the firmware doesn't match on the two machines. This happened to a co-worker of mine once, and I got to learn some colorful new words.
posted by tomwheeler at 9:19 PM on November 13, 2011