My computer cant detect 2 external hard disks

Asked By 220 points N/A Posted on -

I have 2 western digital 1 terra byte hard drives and they both work fine when I connect them independently to my computer but now when I wanted to transfer data from one onto another I plugged them into my USB ports but only one will show up in my computer.

I tried reconnecting them to different ports than those I used earlier but still the problem persists. It won’t be an issue of power since I am connecting both of them to my laptop. Since I have tried that also with my laptop connected to the charger, I would be glad for any help?

Best Answer by Gill Bros
Best Answer
Best Answer
Answered By 205 points N/A #106562

My computer cant detect 2 external hard disks

Is it Possible to connect 2 External Hard Disk Drive into a Laptop? We are sure that if an external hard drive connected to your USB port alone works fine is a good device. Removing the other device and connecting another one which also works fine, there are no problems in your port and to your device.
But when connecting both of them doesn’t work, we therefore conclude that the power supply is not enough. Because connecting of device at the same time with the same specifications doesn’t conflict each other.

Connecting to external hard disk drives into a laptop at the same time is the same with connecting two USB flash drives at the same time on a laptop. Most of the USB drives today getting power on the USB port. USB cables connected to a USB port has 4 terminals. Here are the details of USB Port ping assignments and the color of the wire in the USB cable connected to it.

  1. Vcc (+5 Volts DC) – Red
  2. + Data – White
  3. – Data – Green
  4. Ground – Black
  5. NC (No Connection) – Shielded Wire

The Vcc or the +5 Volts DC is the cable or wire used to supply the power of a USB Device. If your computer or laptop’s power supply wattage is low and not enough to supply the whole system including additional USB device, additional device won’t work. 600 Watts of power supply is enough to supply the system board and inside peripherals include up to four additional devices.

Some external drives like CD/DVD Writer and Hard Disk Drive have their own power supply. This kind of external drives will lessen the load of your power supply because the source of its power comes from the outside supply.

Some devices of this kind use USB power with special cable design to strengthen the power signal comes with the device. Cables of these devices are called the “Dual USB power cable for 1000 MA” where the USB plug is dual, the other cable is used for data signals and the other one is used for the power supply. Plug-in the two cables so that the device will gain faster performance compared to a single USB plug. The following illustration shows the cable design.

Dual USB power cable for 1000 mA

Figure 1. Dual USB power cable for 1000 MA

If the cable above fits to your External Drive or this is the cable you are using right now, do not hesitate to plug-in the two USB plug into your USB port. Doing this will increase the power of your device so that your laptop or computer detects your external hard drive.

USB Hub with power supply. There are USB hubs available in the market today that has its own power supply. Using this device will help your computer’s power supply to lessen its load. Purchase a USB Hub with power supply so that the hub will be the one to give power to the USB device you are attaching in.
Upgrading your power supply. The last option is to upgrade your power supply. But before upgrading, you must test your device first maybe on a desktop computer with high wattage to test what is the ideal supply needed to make the device work on your laptop. This will help you to identify the Wattage value of the power supply you are upgrading to in your laptop.


Answered By 5 points N/A #106564

My computer cant detect 2 external hard disks


I also have the same problem with my external drive. My PC does not detect the device with it, when it is plugged in any of the front USB ports but if you plug it in the back of the CPU it still won’t detect it, but after restarting the system that’s the time it will detect the drive. This is due to insufficient power given by the CPU to the external drive.

Modern external drives often consume a lot of power from your CPU. I often remove some devices from my CPU just to accommodate the external drive. The only way to remedy this is to upgrade the PSU (Power Supply Unit) of your PC. The commonly install PSU in the average CPU has a voltage of 500 watts. I recommend upgrading to about 600 to 700 watts. From the looks of it, you might need a whole lot of power to support your 2 external drives.

I hope this will help you.

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