My laptop is almost dead, so I wanted to reuse every piece possible. I have connected my Hitachi 2½" laptop hard drive in my PC, and I am currently using it. Just making sure "Will it blow up?"

I know the laptop HDD uses 5 volt DC to run and the power supply gives 5V and 12V DC by default.

Is there any risk right now? Everything seems to work fine.

  • 1
    Nope. People do this all the time.
    – MDT Guy
    Nov 22, 2013 at 22:02
  • With SATA the electrical and physical connectors are exactly the same between 2.5 and 3.5 inch drives (With pata, the physical connectors were different but it wasn't very hard to switch between them). In addition, SSDs (which are often the boot/primary choice) only come in 2.5 inch flavours, so putting a 2.5 inch drive in a desktop is something that is definitely supported.
    – Journeyman Geek
    Oct 29, 2014 at 13:33

2 Answers 2


Not at all, it will work fine (and I have done it often).

Some logic/reasons and explanations -

The wattage of a device (talking about electronics here, and ignoring stupid extremes like shorting two wires) is the maximum it can draw. The voltage is fixed, and it is the current that varies. Thus you can use a device which consumes less power without issues.

3.5" hard drives are typically used in desktops because they are bigger, and because they have a bigger surface area they are able to hold more data. Right now, the biggest 2.5" drives commonly available are about 1.5tb, while 4tb drives are available in the 3.5" form factor.

3.5" drives also give a performance advantage in some cases (because the outer edge of the disk is spinning faster data located here, large blocks are quicker to read).

SSD drives are pretty much uniformly 2.5" or smaller, and when mounted in a desktop are put into a bracket. SSD's, btw, use a lot less power then hard disks.

BTW, the power output supplied by the pc is 5/12 VOLT DC (not 5/12 watt, and not AC). A USB device is 5 volt, so it is possible a wall supply used to drive an external hard drive is 5 volts, 12 Watts - again, DC. This is not really relevant to making things work though.

  • I have a 240GB SSD for my desktop. If I use my old laptop that has 5400 RPM 500GB HDD (alongside SSD), will it noticeably affect my performance?
    – puretppc
    Jul 14, 2016 at 16:58
  • dont understand the question. How would you fit the SSD to the Laptop? If via USB converter, is it USB3?
    – davidgo
    Jul 14, 2016 at 20:07
  • I am planning to use both an SSD and HDD on my desktop. I was thinking that instead of buying a new HDD that has 7200 RPM, should I just transfer my 5400 RPM HDD from my desktop to my laptop instead? If so, how much worse will the performance be? Or will it not affect the performance since I boot off the SSD normally?
    – puretppc
    Jul 15, 2016 at 1:25
  • I still don't understand. How do you intend to use 2 drives on your laptop? Assuming you can do that, then if you use the 5400 RPM drive from the desktop in your laptop then this should only slow down when you are reading data off that drive - so you would keep the OS and programs on the SSD and large data files on the HDD for the best of both worlds.
    – davidgo
    Jul 15, 2016 at 1:47

No, it's not risky at all - I have been building custom PC systems since 1991 and have been using laptop hard drives in all my custom builds for almost eight years. My latest build, ZEN, uses a 1TB Seagate/Samsung SpinPoint 2.5" HDD. In fact, I strongly recommend using a laptop HDD in a desktop to all my customers!

The two biggest advantages are low power consumption and sturdiness - laptop hard drives are designed to be sturdy and moved around a lot while inside the laptop, and they use very little power.

The obvious downsides are the rotation speed and capacity, but as I have two 2TB external hard drives, having a 1TB for the main system drive is big enough for me. Also the power and SATA connectors on a laptop HDD are slightly more fragile than on a desktop HDD, so you do need to be careful where you place the laptop HDD as some power and SATA cables can place strain on the connectors.

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